Open with a sweaty woman hotwiring a car. It seems she's bleeding several from her stomach. She crashes into a mailbox and staggers into an apartment building. She knocks on a door and we see that it is Thirteen's (Olivia Wilde
) place. "Darrien?" Thirteen asks, clearly knowing the woman. Darrien tells Thirteen she wants to be stitched up but refuses to go to the hospital. This is a prison acquaintance of Thirteen's. Both are worried about going back. Ultimately, Thirteen promises not to take Darrien to the hospital.
House (Hugh Laurie
) brags about his new leg strength to a prostitute. He attempts to prove it by lifting two huge amplifiers. But he gets a cramp in his leg and drops one on a glass table. House notices he's out of the experimental drug he's been taking.
Thirteen examines Darrien's stab wound and thinks a cut to her liver has been clotted off. She thinks Darrien might be stable, but will check her blood pressure constantly to see if there is a bleed she's missed.
Foreman (Omar Epps
) comes home to find Taub (Peter Jacobson
) having a serious talk with Ruby. After she leaves, Taub tells Foreman she's pregnant.
Darrien says the drug house she was in got raided by the cops. The guy she was with stabbed her to create a distraction. Darrien says it's her fault she started using again. Thirteen finds no pulse in one arm, but completely normal pressure in the right arm. Thirteen calls Chase (Jesse Spencer
) and asks him to bring over a portable ultrasound, saying it is for a plumbing emergency.
House goes to see the scientist who has been conducting the muscle re-growth study on rats. To his horror, the guy tells him all the rats are dead, the result of massive tumors caused by the drugs. He says the first sign was cramping. A few days later, the rats were dead.
Chase realizes Thirteen was full of it and helps with Darrien. Thirteen tells her about being in prison and calls Darrien "my friend."
House gives himself an MRI. It doesn't appear as if the results are good.
Chase correctly guesses the reason why Thirteen went to prison. Darrien (who has Hepatitis C) "saved" Thirteen when they were inside. Darrien's arm is starting to go numb. They find a mass in her arm compressing the artery.
Foreman and Taub go to a strip club. Taub says he doesn't want to keep the baby, but Foreman correctly guesses he's considering it.
Chase and Thirteen drain the mass from Darrien's arm, but Chase is worried they don't know what it was or whether it will come back. They wonder if her body used up her clotting factors dealing with the stab wound, which could mean she's at risk for bleeding in her brain or hearth. Chase thinks Darrien needs to go to the hospital, but Thirteen keeps her promise.
House is going to perform surgery on himself in his own bathtub.
With Chase gone to pick up meds, Thirteen asks Darrien about why she's blaming herself for getting back on drugs. Darrien isn't talking.
House struggles to remove the first of what looks like several tumors in his leg. But after the first he can't keep his hands from shaking and begins to make mistakes. He calls Wilson (Robert Sean Leonard
), but his friend doesn't hear the phone while asleep.
Taub gets a lapdance and asks the stripper the best way to tell a woman you don't want to have a baby with them. House calls him as well, but Taub assumes House is drunk or something and doesn't pick up. Taub notices a mole on the stripper's back and asks if she had it looked at. After he touches it for a second time, the stripper has Taub thrown out.
Darrien sees a young man with a gun at the foot of her bed. She begs him to put the gun down and tells him to put it down. The kid cocks the gun, but a shot hits him in the forehead before he can fire. Thirteen runs to the room to find Darrien hallucinating. She says "I'm sorry" over and over again.
A desperate House calls Cuddy (Lisa Edelstein
). Cuddy wakes to find daughter Rachel lying in her bed watching a pirate cartoon. She answers House's call.
Chase returns. Thirteen thinks they need more clotting factor. He is convinced they must take Darrien to the hospital and get her a CT scan. Thirteen sticks by the fact she made a promise. Chase tells her he's going to take her anyway. They have a brief scuffle in which Chase knocks her to the ground.
Cuddy goes to House's place. She calls him a moron. He was worried about surgeon taking more of his leg muscle and asks her to remove the second tumor. She says "absolutely not."
Chase drives Darrien and Thirteen to the hospital. He promises he will fudge the paper work so the police don't know she's there.
In the car on the way to the hospital, Cuddy tells House she thinks he was trying to make his life better. She thinks he's unhappy and unhappy people do reckless things.
Darrien tells Thirteen and Chase she used to be a cop. In the line of duty, she was forced to kill a 19-year old when he went for his gun. That was the event starting her down the road to drugs. Darrien loses consciousness.
Cuddy figures out it was House who got Rachel watching the pirate show.
Foreman finds Taub in the back of the strip club waiting for the stripper to ask about the mole. Foreman thinks he's going to get himself beaten up by the bouncers and wonders if Taub thinks he needs to punish himself. Foreman leaves.
During Darrien's scan, Chase says Thirteen is holding onto this promise she made to Darrien because of the promise she made to her brother to help him die. If she doesn't keep all promises, her defense mechanism crumbles. There is no bleed in Darrien's brain, but she starts to shiver on the table. She must have an infection.
Cuddy and Rachel bring House to the hospital. Cuddy thinks House might be going into shock and goes to find a nurse. While she's gone, Chase and Thirteen call House. Unaware of his predicament, they ask about Darrien.
Sitting in his car, Taub debates calling Ruby but changes his mind.
House thinks they should figure out exactly when Darrien contracted Hep-C. Thirteen thinks based on medication she was taking in prison, she must have had it for more than a decade. Since Darrien started taking drugs after the shooting, House thinks they should look there.
Taub also considers calling his ex-wife, but changes his mind when the stripper walks out the back of the club. He tells her he is actually a doctor. She freaks out, calling him a pervert and thinking he's there to hurt her. She pulls out a gun and has him kneel on the ground with his back to her. She cocks the gun but ends up fleeing the scene. Taub is understandably rattled.
While Thirteen looks online for Darrien's shooting, she tells Chase he was right about everything. She sees the shooting happened in 2008. The only reason newer Hep-C would look like older Hep-C is if she had a parasite.
House is about to go into surgery. Before being taken away, he asks Cuddy to be in the OR. He doesn't trust the doctors will only remove muscle tissue or his entire leg as a last resort, but he trusts her.
Darrien wakes up. Thirteen tells her she's going to be fine. Darrien looks down and sees she's wearing handcuffs and notices a cop standing outside her room. Thirteen says she had no choice and thinks Darrien will thank her one day.
While waiting for House to wake up, Rachel says she misses him. Cuddy thinks she should write him a letter.
Taub goes to see Ruby. He says during the moment he thought he was about to die, all he thought about was a former patient who seemed okay with news of terminal cancer because he had raised good children and knew the world was a better place. Taub wants to have the baby with her.
In the locker room, Thirteen tells Chase she's terrified she'll destroy her life trying to forget something justified. She doesn't think it's something he could possibly understand. He says with tears in his eyes: "Let's grab a coffee." He is obviously thinking about Dibala.
The team comes back together the next day. Nobody talks about what happened the night before. House isn't there.
We cut to House waking up in recovery with Wilson at his side. Both of his legs are there.Wilson tells him he was very lucky. House tries to walk to the bathroom himself and staggers. Wilson tells House he can't continue living his life this way.