This book begins with the boys on a fishing vacation in Maine, when Joe claims he’s seen Iola Morton alive and well.
Tropes found here are
- Butt-Monkey: Henri and Jacques get clobbered by the boys three times. Ivan Orlov is on the receiving end of a double team too. Twice.
- Did Not See That Coming: Although Frank II and Frank, as well as Joe II and Joe, are equally matched in a fight, the boys’ differing fighting styles mean that Frank II cannot fend off Joe’s street fighting, while Joe II cannot neutralize Frank’s martial arts.
- Girl of the Week: Subverted, since the story revolves around Joe's girlfriend, Iola, seemingly being alive after all, and the boys' attempts to save her from the Lazarus gang. But it's then double-subverted by the end, when she's revealed to be a random girl named Sally Collins who was kidnapped and turned into a clone of Iola. The boys plan to have her restored to her original identity and sent home, while Iola really is gone for good.
- Gone Horribly Right: The Lazarus gang does such a good job of programming Iola's clone that she is able to convince Joe that she's the original. Unfortunately for Lazarus, this backfires on them when they try to have her kill the Hardys; her memories are so well-programmed that her love for Joe means she can't bring herself to murder them, and all three of them escape together and bring down the gang.
- Kill and Replace: The Lazarus team created exact duplicates of the boys to eliminate and replace them. They did this so the doubles could get close to both the Gray Man and his boss, the Director of the Network. The both of them would be eliminated, at which point, the Lazarus Leader would assume the identity of the Gray Man and become the head of the most secretive spy agency in the world.
- Love Redeems: At the climax of the book, Iola—revealed to actually be a clone, Iola II—is supposed to kill the Hardys. However, since she has been programmed with the original Iola's thoughts and feelings from her diary, Joe and Frank are able to invoke her and Joe's deep love for each other to break through her programming and convince her not to kill them and escape with them instead.
- Secret Test of Character: The Hardy Boys unintentionally pass one with the Gray Man, who had already been visited by their clones, the latter of whom had convinced him that they were the real ones. Frank reluctantly decides to force the Gray Man to tell them where their clones went through torture, only to find that he just can't bring himself to do it; this, plus the fact that Joe couldn't watch it happen, convinces the Gray Man that they're the real Hardys and are telling the truth, since he knows the real enemies are far more ruthless and would have no problem using torture.
- Spot the Impostor: Joe tries this with Iola when Frank points out she might be a clone, and after she can correctly recall every detail he can think of about herself, him, and their relationship together, becomes convinced she's the real deal. Unfortunately for him, as Lazarus reveals near the end, Joe was unaware that Iola kept an "extremely detailed" diary, which they stole and used to program the clone well enough that she could pass for the original.
- Yank the Dog's Chain: For a large portion of the book, it looks like Iola is alive after all, as she claims that the Assassins pulled her away from the car in the first book right before it exploded, and Joe's primary motivation is saving her from the Lazarus Gang. At the climax, it's revealed that she's not the real Iola, but just a very well-programmed clone, meaning that Iola probably is dead after all. To rub salt in the wound further, after he's captured at the end, the Lazarus leader refuses to reveal the truth to Joe one way or the other.
- You Have Outlived Your Usefulness: At the climax of the story, Lazarus orders Iola II to kill the Hardys and leave the compound after 15 minutes have passed. Turns out he set a bomb to destroy the entire building after 10 minutes, and even locked the door to the room the three of them were in, just in case Iola II tried to leave early. When she's confused by this, Joe directly tells her, "They didn't need you anymore."
