Instead of reimagining the classic superheroes as they would be today, Cooke created a story firmly set in the 1950s and took the superheroes as they were in The Golden Age of Comic Books and made them believable. Even the art work itself is very similar to comics of that era, with only the layout being modernized. The plotline is broad-ranging, featuring dozens of characters in the DC Universe including Superman, Batman, Wonder Woman, Green Lantern, The Flash, Martian Manhunter and many more.
Part of this experiment was Cooke trying to figure out a reason why various characters changed in the switch between The Golden Age of Comic Books and The Silver Age of Comic Books. It was easy enough with Legacy Characters like Green Lantern, but Batman went from a dark and menacing figure who wore grey and black into someone more kid-friendly with blue and yellow highlights. In the story, Batman changes it after frightening a child he was trying to help, rather than the criminals he wants to scare.
The story took the paranoia associated with McCarthyism and how it would affect the costumed heroes. "Idealistic" heroes like Superman and Wonder Woman are forced to sign loyalty pacts, while Batman remains underground and outside any government control. Even Wonder Woman starts to ignore "Man's World" and returned to Paradise Island.
Hal Jordan is a fighter pilot for The Korean War who gets shot down, then recruited for a mystery space program. He is soon contacted by a dying alien and given the Green Lantern ring.
The Flash finds himself struggling to remain doing his super-heroics without bending to the will of the government, so he announces his intention to stop being a hero altogether on television.
A scientist's experiment results in an alien being teleported from Mars. The scientist suffers from a heart attack and dies, and the Martian gradually assimilates himself into human culture using his shapeshifting abilities but is ever aware of his desire to return home.
While all these internal struggles continue, a monster slowly descends upon civilization. It has psychic powers that leave miscellaneous people (and the Martian) aware of its existence. As the threat grows in intensity, everyone, both superhero and the government, sets aside their problems to confront this menace as a united League.
The comic was given an animated Direct-to-Video film adaptation titled Justice League: The New Frontier in 2008, with the voices of David Boreanaz as Hal Jordan, Kyle MacLachlan as Superman, Jeremy Sisto as Batman, Lucy Lawless as Wonder Woman and Neil Patrick Harris as The Flash. Keith David's baritone voiced the omninous and faceless Center. The film was produced by veteran DCAU man Bruce Timm and paid strict attention to the comic, lifting the majority of dialogue and scenes from the comic straight into the film. The film is part of the DC Universe Animated Original Movies line.
Critical reception was enormously positive, the only complaint being how short the film was. Compared to other DTV comic book films, including those from Marvel and prior DC videos, this film was considered a breakthrough for mature Western Animation.
This story provides examples of:
- Adaptation Distillation: There were almost no storylines omitted entirely from the comic to movie; even those that were taken out had a passing mention. This is especially notable due to the short length of the movie. In just 75 minutes they managed to give in-depth origin stories to Green Lantern and Martian Manhunter while giving ample screentime Superman, Wonder Woman, Batman and the Flash and driving the main story forward.
- Adaptation Expansion: In the comic, Batman opts out of participating in the final battle, feeling as though he would be more helpful backing the heroes through Wayne Enterprises instead. In the film, he takes over Green Arrow's role in the fight.
- Alternate Continuity: Relative to the main DC universe. In the collected edition, space-time-traveler Rip Hunter shows up in a short prologue to basically say it's not important which timeline or Earth this takes place in.
- America Saves the Day: The Final Battle with the Centre is specifically described as America's greatest challenge and J'onn J'onzz specifically claims that fighting the Centre will require the efforts of "all Americans."
- The Bad Guy Wins: In one of the subplots. Try as he might, John Henry can't beat the Klan.
- Badass Boast:
- "You really think you can hit me? It's been tried before." — The Flash, to a soldier pointing a rifle at his head, from point blank range.
- Batman delivers a memorable one to Martian Manhunter when they first meet:"My instincts tell me that you're to be trusted. But make no mistake: it took a $70000 sliver of meteor to stop the one in Metropolis. With you all I need is a penny for a book of matches."
- Badass Normal: The American government has started recruiting these to make up for the lack of superheroes, so these show up a lot. Let's see, there's the Challengers of the Unknown, the Blackhawks, the Suicide Squad, the Losers, King Faraday, the Sea Devils, Green Arrow... and Batman.
- Big Bad: The Centre, a Genius Loci island out to Kill All Humans.
- Big "NO!": The Centre, when it's destroyed. Though it's unclear if he screamed because he's killed or in despair for his failure to cleanse the Earth of humanity.
- The Cameo: Vandal Savage appears as a "mandatory guest" of the U.S. government.
- Cassandra Truth: Adam Strange tries to warn Earth about the Center, but is locked up in Arkham. The government is still afraid of him, though.
- Cliché Storm/Troperiffic: In-Universe; Martian Manhunter bases his human identity of John Jones on detective shows. As a result, John Jones is the single most over-the-top detective you have ever seen. Slam Bradley thinks he's ridiculous, but likes him since he's one of the few good cops in Gotham.
- Comic-Book Fantasy Casting: Word of God states that Hal Jordan is based on actor Burt Lancaster. Captain Cold is modeled after fellow comics writer Grant Morrison.
- Cowboy Cop:
- Wonder Woman.
- Superman, too. He's just discreet about it.
- Cult: The unnamed purple robed men under the thrall of the Centre that Batman dispatches.
- A Day in the Limelight: Hal Jordan, the Martian Manhunter, and the Flash are the POV characters while the big name characters Superman and especially Batman are relatively Out of Focus.
- Death Seeker: Task Force X, hence the nickname "Suicide Squad." Also Hal Jordan and John Cloud, though Hal gets over it. The trope is deconstructed, as the problems with relying on such unstable individuals are addressed. Jess Bright loses it, sabotages the spacecraft in mid-mission, and causes an international crisis.
- Deep South: Part of the story deals with John Henry, an African-American vigilante who takes on The Klan.
- Deliberate Values Dissonance:
- Hal Jordan is treated like a coward because he doesn't want to kill people, and Flagg thinks this makes him a Communist sympathizer.
- Not to mention all the smoking Carol Ferris does. Or Hal making a wrong step when he meets her because she's a woman running a company (he claims he was just going to say she was young).
- Disney Death: Superman.
- Do with Him as You Will: Wonder Woman frees a group of sex slaves, disarms their captors, and lets them decide what to do next.
- Dying Moment of Awesome: King Faraday (in the movie)/John Cloud (in the comic) jumps into a T. Rex's mouth with a pair of live hand grenades.
- Eagleland: A central theme. It's a Type 2, but eventually evolves into a type 1.
- Earn Your Happy Ending
- Eldritch Abomination: The Centre, a living island with the ability to spawn an army of even more eldritch-looking dinosaurs. And is mentally linked to them, which is what does it in-the death of the T. Rex mentioned in Dying Moment of Awesome disrupts its focus for a minute, leaving it open to a fatal strike.
- End of an Era: Part of the story deals with the transition from the Justice Society to the Justice League, along with superheroes with more scienctificaly-based origins compared to most of the Justice Society's magic.
- Enemy Mine: Subverted at first. The superheroes came to help the military, but they don't want their help. A soldier even threatens to shoot Flash if they don't leave. Not helping is the Flash tempting him. Fortunately, Superman arrives to stop it and calls them out for continuing their petty hatred with one another while the world is in danger.
- Business rivals Wayne Enterprises and LexCo put aside their animosity to lend equipment to those fighting the Centre together.
- Everything's Better with Dinosaurs: No. It is not.
- Fire-Forged Friends: The Martian Manhunter and Faraday.
- Foreshadowing: The light fixtures in the Ferris Aircraft Corporation lobby look suspiciously like the Green Lantern symbol.
- Freeze-Frame Bonus: In the comic, Bruce Wayne and Selina Kyle witness Captain Cold's robbery. The animated film keeps them in the foreground for a second or two, with no speaking lines.
- Good Is Not Nice:
- King Faraday.
- Batman, pre-Robin.
- Wonder Woman is a relatively mild case.
- Gondor Calls for Aid
- Heroic B.S.O.D.: Hal Jordan spends most of the story in one over killing a Korean soldier in self-defense. To make it worse, at that point he knew that the war was over, but couldn't communicate it to the soldier.
- Heroic Sacrifice: Col. Rick Flagg and Faraday.
- Humans Are Bastards:
- The reason for the Centre to destroy them all. The first atomic bombs were the push it needed.
- Also Martian Manhunter chose to return to Mars after seeing some people are apathetic towards Flash quitting, as well as John Henry being executed by the Klan for standing up to them and nobody giving a shit about it.
- Intrepid Reporter: Lois Lane, who is firmly on the government's side at the beginning of the story.
- Ironic Echo: "There's the door, spaceman."
- Kid-Appeal Character: In-universe, even: after terrifying a child he saves, Batman undergoes a radical image change through a costume update and the adoption of Robin, claiming that he's out to scare "criminals, not children".
- Know When to Fold 'Em: Comic book only. After gathering evidence on the Center, Batman decides that he's not cut out for cosmic beings and Gotham keeps him too busy as it is, so he hands the evidence over to a guy who can deal with it: Superman.
- Laughing Mad: The cult leader, right after the Centre spoke through him.
- Legacy Character: Hal Jordan and Barry Allen are heirs to the legacies of the first Green Lantern and Flash. At the end, the Justice League -heir to the Justice Society- is born and its members' successors -Robin, Kid Flash, Supergirl, Wonder Girl, Aqualad and Speedy- come together in the Teen Titans, led by Black Canary.
- Let's You and Him Fight: A Superman vs. Batman fight broke over the Super Registration Act. Superman lets Batman win. The whole fight was staged by Clark, Bruce and Diana so Superman wouldn't have to arrest his buddy.
- The Men in Black: King Faraday.
- My Fist Forgives You: Flash is able to work with Faraday despite Faraday trying to arrest him. You know, after Flash punches him in the face. Faraday was kind enough to let it slide.
- Mythology Gag:
- Captain Nathaniel Adam sacrifices himself by detonating the atomic bomb he's carrying. Don't worry, he'll get better, eventually.
- The comic ends with the Justice League confronting Starro, echoing the classic cover of The Brave and the Bold #60.
- Negated Moment of Awesome: Superman rallies and unites the heroes, gives a Rousing Speech, and then charges the Center... only to be instantly and casually knocked aside. The Mass "Oh, Crap!" from everyone else is almost comical.
- No Celebrities Were Harmed:
- The President is never named, even in the credits, but the voice at the end of the movie sounds just like John F. Kennedy, and gives a modified version of JFK's New Frontier speech.
- Ted Grant defends his title against a young black fighter named Clay but we never learn Clay's first name or see his face and he's also at least eight years older than Cassius Clay/Muhammad Ali. In the movie he looks like Ali but is renamed "Cooke".
- No Sympathy: After Flash's public retirement, some people don't care or are glad he quit. This was the last straw for Martian Manhunter in his decision to return to Mars.
- Precision F-Strike: John Henry, wounded and hiding from the Klan, begs a little blonde girl for help. Her response: "The nigger's over here!"
- Poor Communication Kills: The whole reason Hal had to kill in self-defense was because the North Korean jet pilots and ground soldiers hadn't learned that the Korean War had ended, and neither of them spoke each others' languages.
- R-Rated Opening: The series opens with Hal crashing in enemy territory, tussling with a North Korean soldier, then killing him.
- Raygun Gothic
- Red Scare: There is notable paranoia and discrimination occurring over who is a communist sympathizer. The Flash was even accused of being a communist sympathizer due to his red costume.
- Role Reprisal: Aquaman is voiced by Alan Ritchson, reprising his role from Smallville. In addition to that, Bugs Bunny is voiced by Joe Alaskey, reprising his role from various Looney Tunes projects, most notably Looney Tunes: Back in Action.
- In the French dub (which was done MANY years after the movie was made, unlike the majority of the DC Universe Original Animated Movies), several voice actors from other adaptations reprised their roles here:
- From the DC Animated Universe: Emmanuel Jacomy as Superman/Clark Kent and Véronique Augereau as Lois Lane.
- From The Batman: Adrien Antoine as Batman/Bruce Wayne, Alexis Tomassian as Robin/Dick Grayson, and Christophe Lemoine as the Flash/Barry Allen.
- From Green Lantern: First Flight: Marc Perez as Abin Sur.
- From Superman/Batman: Apocalypse: In addition to Superman and Batman, Delphine Braillon as Wonder Woman/Diana Prince.
- From Batman: The Brave and the Bold: In addition to Superman, Batman, Wonder Woman, the Flash, Lois, and Robin, Philippe Peythieu as Martian Manhunter/J’onn J’onzz, Michel Vigné as Aquaman and Captain Cold, and Nicolas Marié as Dr. Magnus.
- From Young Justice: In addition to Superman, Batman, Wonder Woman, the Flash, Martian Manhunter, Aquaman, and Captain Cold, Vincent Ropion as Ray Palmer, and Michel Vigné as King Faraday.
- From Green Lantern: Pierre Tessier as Green Lantern/Hal Jordan.
- From Green Lantern: The Animated Series: In addition to Green Lantern, Céline Melloul as Carol Ferris.
- The bar that Hal goes to after getting the ring (in the film) is very similar to the bar at the beginning of The Right Stuff. In the comic book, Hal actually goes to the Happy Bottom Riding Club as a child and meets Chuck Yeager and Pancho Barnes there.
- Slam Bradley looks an awful lot like Robert Mitchum, which ties in with his Film Noir detective persona.
- Sliding Scale of Idealism vs. Cynicism: It actually slides during the course of the story. It starts pretty cynical, but slowly gets more idealistic as the story progresses. How idealistic? The story ends with the friggin' formation of the Justice League of America, that's how much.
- Society Marches On: In the Silver Age Green Lantern books, Hal used to call his sidekick Tom "Pieface," a slur for Asians. He uses the name exactly once in New Frontier, and Tom immediately snaps at him and grabs him by the front of his shirt.Tom: What did you call me, white-bread? Do I look like a pastry to you or something? The name's Tom, got it?
Hal: Whoa... Tom. I got it. I got it.
- Sophisticated as Hell: Billy Batson is able to keep up with the other magical heroes on their discussion of how much involvement they should have in the fight against the Centre...and complain about getting brain freeze from eating too much ice cream without missing a beat.
- Starts with a Suicide: The film opens with a writer of a children's book, who is aware of the Big Bad, shooting himself in the face in despair.
- Statuesque Stunner: Wonder Woman, per tradition. But a memorable (and deliberate) example comes when Superman confronts her in China. She is sitting on a table for most of the conversation, and when she gets off it's shown that she is taller than him.
- Storyboarding the Apocalypse: A particularly creepy example, wherein the Centre's plans for humanity are communicated via the writings of a children's author — specifically, a Dr. Seuss Expy. Who then shoots himself.
- Superman Stays Out of Gotham: Captain Marvel, Zatanna, the Spectre, Doctor Fate and the Phantom Stranger meet on the Moon to discuss the situation, and decide it's not their place to take part.
- Super Registration Act
- Supporting Protagonist: Subverted. Hal Jordan doesn't have a huge impact on the story at first. But then, he is Hal Jordan.
- Take That!: Superman and Wonder Woman seem to agree that Richard Nixon is an "oaf."
- Technical Pacifist: Hal Jordan gets a lot of flak for this since he's in the Air Force. He eventually decides it's okay to kill in self-defense. (And even before then, he sets enemy pilots up to be shot down, apparently feeling that this isn't the same as doing it himself.)
- Training the Peaceful Villagers: We never get to see it, but Wonder Woman trains a group of freed sex slaves in anticipation of a coming war.
- Ungrateful Bastards: When Flash announce his retirement due to distrust from the public and the government, most people in the restaurant J'onn's eating at either don't care or are glad he quit.
- Underwear of Power: As drawn by Cooke, notable for looking like boxer shorts instead of the usual briefs on the men.
- What Happened to the Mouse?:
- Faraday reveals Hourman is still alive and in a government cell, but he's never seen or mentioned again. Not even after the world's saved and everyone decides to work together.
- Were any of the Amazons able to get away from the Center or is Wonder Woman the only survivor?
- What Have I Become?:
Batman: Let's just say I dress this way to scare criminals. Not children.
- Part of Batman's motivation in changing his look and methods. He realizes that he's taken the dark avenger thing a little too far and has become a monster to the very people he's trying to protect.
- John Henry's death is heavily implied to be a big wake up call to Americans to finally start realizing how ugly their bigotry is.
- What the Hell, Hero?: Superman is shocked that Wonder Woman freed slaves and sat by and watched as they killed their tormenters. Wonder Woman argues that it was necessary for them to get their pride back, and that she's doing more than Superman is about it.
- Where the Hell Is Springfield?: Central City appears to be in Illinois, given that one character refers to its resident superhero as "the Illinois Flash."
- World of Badass: One of the main reasons the book is so awesome is that it works really hard to show you that Superman and Batman aren't the only badasses in the DCU.