Mash: What is it?
Drake: Blood... Well, with my job, I'm used to smelling stuff like this.
Mash: Look, the drops form a trail.
Drake: Looks like the wound itself wasn't too bad. A flesh wound.
Mash: It's our only clue. We should follow it!
Following footprints in the mud or using hounds to sniff out a scent are just two of many ways to track down fleeing persons, but none are as dramatic as following a trail left by the mark's blood. Not only does it lead the pursuers right to their target, but it also highlights the fact that the fleeing character is wounded, creating additional drama by constantly making him weaker and bringing him closer to death.
In a variation, the trail of blood comes from a body that has been dragged away, but in that case the amount of blood rarely leaves any hope that the person could still be alive. Still, any characters who come upon such a trail will also follow it to whatever gruesome sight awaits them.
In other cases, the heroes or the villains would find themselves to be vulnerable when they follow it to a bad situation, such as an ambush or a sneak attack.
- In Ghost in the Shell: Arise, Batou and Togusa follow a red blood trail when they were investigating a suspect behind a series of bombing attacks involving prosthetic limbs. While it led to a crumpled bullet head, the two detectives were caught in an ambush from the back.
- Ninja Scroll. Shijima leads off Jubei this way, by stabbing a fox. He then doubles back while Jubei is following the false trail and kidnaps Kagero.
- In Durarara!!, during Izaya and Shizuo's final fight, Izaya fails to kill Shizuo and is hit into a building with a metal beam. Izaya survives, but coughs up a pool of blood and leaves a trail as he tries to escape, making it easy for Shizuo to track him.
- Three Leaves, Three Colors: Parodied in episode 3, where the girls find a suspicious red trail once they arrive at the cake shop. It turns out that the "blood" wasn't blood at all, but spilled jam, which Shino carelessly scattered while she was having lunch.
- In Fullmetal Alchemist, after Lan Fan's arm is injured and she flees the fight, Wrath starts tracking her by following the trail of blood. When he finally reaches the end though, he finds out that she completely cut her own arm off and tied it to a stray dog, so he's been following the wrong trail the whole time. Wrath merely comments "That was well-played, girl."
- At the end of V for Vendetta, Evey follows a trail of blood to find V.
- In a Dutch comic of Donald Duck, the Beagle Boys steal money from Scrooge McDuck, but don't notice the new money paper is razor-sharp until they dive into a pile of it. When they get arrested, they taunt the police by saying: 'You'll never find where our hideout is!' but they soon retort with: 'That's easy, we'll just follow the drops of blood.' and point to a blood trail nearby.
- Dungeon Keeper Ami: From Interrupted Plotting, it's how Rabixtrel is first found, as a trail of blood from his victims, leads scryers to him:
"Let's see if whoever is running that place has managed to attract something other than skeletons and ghosts by now."
"I got something," one of the magicians called, stroking his beard.
Ami hurried over, followed by the others. "That quickly?"
"I just followed the trail of blood," the gangly wizard answered, gesturing at the screen with a gnarled hand. He soon felt crowded when everyone leaned in around him to get a better view of the cavernous hall he had found.
- In The Freakmaker, Tony's escape from the lab is showing by the camera following a trail of blood across the laboratory floor to the French windows when it disappears outside into the night.
- House of Usher: After Madeline claws her way out of her coffin, Phillip eventually finds her by following the trail of blood from her cut-up hands.
- In I, Robot, Spooner notices that the escaped robot is leaking fluid after getting shot. Instead of following the trail, he goes straight to the factory, where he knows Sunny will go to to repair himself.
- Late Phases: The werewolf leaves one after the first attack, with the blind protagonist enlisting a mailman to help him follow it to try and find whose house the werewolf went to and identify him.
- In The Lord of the Rings: The Two Towers, Gimli tracks the hobbits in Fangorn by following the trail of blood left by the orc chasing them.
- In Nightcrawler, the protagonist is first to arrive at a mansion where a double murder has taken place. With his camera he follows a trail of blood upstairs where he finds a body in the sleeping room.
- A Nightmare on Elm Street (1984): During Nancy's classroom nightmare, she follows Tina's corpse down the school hallway, which has left a bloody trail on the floor behind it.
- At various times throughout Predator, Dutch and the alien track each other via following their bloodstains.
- This happens on three occasions in Revenge (2017), the French Rape and Revenge movie. The first time, the villains follow Jen's blood trail from the canyon to the lake, where she loses them by entering the water. In the other two, Jen gets in the first shot, then follows the blood trail only to find the man has doubled back and is waiting in ambush. The first time she only survives because he's been shot in the shoulder and can't aim properly. The second time she's more wary and sees the blood flowing from where he's concealed himself behind the doorway, despite a clear blood trail leading across the room to the window.
- While it's not technically blood, near the end of Short Circuit 2 Johnny 5 suffers damage to his battery before going on a Roaring Rampage of Revenge, forcing the rest of the protagonists to follow the trail of battery acid and help him.
- When Ballard is taking refuge in the church in Silver Lode, his pursuers notice a trail of blood leading up to the bell tower where he's hiding.
- Thunderball: Shot in the ankle, Bond leaves a blood trail that causes mooks to follow him to a nightclub. Bond, ever the ladies man, dances with the female leader of the group, and manages to get her to take the bullet meant for him.
- The Woman in Green, one of the later black-and-white Sherlock Holmes films starring Basil Rathbone, has a variation. Holmes and Watson walk into a police detective's office to discover the man has been shot dead. Instead of following the trail of blood to the body, Holmes analyzes the trail of blood the dying detective left to determine the probable sequence of events during the murder.
- Exploited in The Sapphire Rose. Sparhawk and his friends try to navigate a maze by following blood drops from a wounded enemy. Then they discover 1) the blood drops aren't from any of the injured Zemochs, because 2) they aren't blood, and 3) they're only there to keep people in the killing-ground maze, the real entrance to the temple is elsewhere.
- Subverted in Temple of the Winds. Kahlan and Nadine are tracking a badly wounded wizard through tunnels. When they reach a fork, Nadine says they should follow the path with blood... but Kahlan points out there was no blood before the fork, so it's obviously a false lead, and they should follow the other path - where there are no people.
- Invoked in the Burn Notice season 3 premiere. Michael uses the blood from self-inflicted cuts in his wrist (from cutting himself loose after being duct-taped to a chair) to leave a trail that guides his pursuer into an ambush.
- CSI likes this. It often shows up when they're looking for a primary crime scene after someone dies elsewhere. In one ep,a guy was run over by a taxi but it was clear he was stabbed first. The team followed the blood trail to a basketball court where he was first stabbed. He then made it to the highway and was run over.
- Dexter does this in the fifth season when he has to track a wounded man in a warehouse. In areas when he loses the trail of blood, he just breaks out the luminol and tracks drops invisible to the naked eye.
- Father Brown: In "The Passing Bell", Father Brown follows a trail of blood to find the Body of the Week hidden out of sight in the corner of the belltower.
- In the Firefly episode "Bushwhacked", Jayne is ambushed in a derelict ship's mess hall and wings his attacker with his revolver. Simon spots a trail of blood drops they follow to the man's hiding place.
- In the episode "Powehiwehi" of Hawaii Five-0, Kono uses a fake blood trail to lure in an armed suspect Danielle, who is the mastermind of the events into an ambush in an isolated room.
- Invoked in an episode of MacGyver. The title character creates a trail of fake blood drops out of chemicals found nearby to throw a pursuer off
- In Orphan Black, the police find that Helena left a trail of blood when she broke into someone's home to treat wounds from her fight with Beth/Sarah.
Art: Just follow the bloody brick road.
- Twice in the Game of Thrones Season 6 episode "No One": Arya uses the blood from her reopened wounds to lure the Waif into her cell, and after their apparent fight in the darkness we see a trail of blood going into the House of Black and White, to create suspense as to which of them survived.
- In Batman: Arkham City you track one of the League of Shadows ninjas using the blood trail left when she cut herself on glass while making her escape. Rather than a thick obvious trail, it's a series of tiny drops that you have to use detective mode to highlight.
- In BioShock these trails include everything from bloody footprints to messages written in it.
- Blame Him: There's some streaks of blood on the floor of the room beyond the first code-locked door.
- There's another one on the floor of the room that contains the first enemy.
- Counter-Strike: In Source, players will leave blood behind if shot. The blood decals are usually away from the player, allowing other players to find out where they are hiding.
- Can be used as a tactic in Deus Ex if the player wishes to pursue a fleeing, wounded enemy. Wounded characters will leave a trail of blood when they run, and a resourceful player can track them.
- In Dead by Daylight one of the ways the killer can more easily catch the survivor players is by watching for faintly luminous red streaks. These appear in the wake of a player after they've been hit by the killer's machete or after they pull themselves out of a bear trap.
- In Dreamfall: The Longest Journey, a trail of blood leads Zoe to the backdoor of the Victory Hotel, which she has to infiltrate. She assumes it is Reza's blood but she never finds Reza inside.
- In The Elder Scrolls V: Skyrim, the sidequest "Blood on the Ice" has the player tracking a serial killer. In order to find his hideout, you have to follow a trail of a dozen or so blood spatters that are about five feet in diameter. The guards somehow failed to notice this, but then the very start of the quest establishes that they really don't give a crap, considering things like the return of the dragons and the Stormcloak rebellion to be far more important.
- Both the Fear and Dead Space series are full of blood trails, but they are usually not relevant, as there are monsters and corpses everywhere else as well.
- Final Fantasy VII. Cloud & company follow one of these when infiltrating the Shinra building for the first time. The song that plays during this section is aptly named "Following the Trail of Blood".
- In the Jagged Alliance series wounded soldiers leave a trail of blood, making it easier to track them.
- In League of Legends, one of Talon's abilities allows him to brutally stab an enemy, which causes them to leave behind a trail of blood that lets him track them even as they enter cover (like bushes)
- During the Shadow Broker DLC from Mass Effect 2, after running down the rogue Spectre Tela Vasir during the big skycar chase and causing her to crash, Shepard and Liara must follow her blood trail in order to find her and take her down.
- In Max Payne, trails of blood feature prominently in Max's nightmares. You must follow them to get out of the nightmare.
- In Pandora's Tower, if you come back to Elena when her meter is critical, she will not be in the observatory's main room, but rather in the cellar. On the way to the cellar, Aeron spots a trail of purplish blood.
- Thief II: The Metal Age has a level called "Trail of Blood", in which you follow a wounded Pagan courier through a forest village and into The Maw of Chaos. It ends when you catch up to your target and find he's bled out.
- Silent Hill 2 has James following a blood trail on a street when he arrives in the downtown area of Silent Hill, which leads him to first encounter with a monster.
- Not blood, but when the German battleship Bismark sank its British counterpart Hood and send the Prince of Wales fleeing the battle, she had still been hit several times and was leaking oil. The oil trail allowed British airplanes to track down the damaged ship and completely cripple it with one lucky torpedo hit, after which it was no effort for the superior British fleet to catch up and blow her out of the water.
- Hunters of all stripes will often follow the trail of blood from something they've just put an arrow or bullet through.
- Sharks are well known for their ability to follow even the tiniest traces of blood in the water over miles. However, they can not smell blood that is dropped into the water any distance away until the currents create a trail the shark can actually pick up and follow.