Football scouts watch a college football practice. After a play, lineman Daryl Bartlett has a fit and attacks the safety, dragging him across the field. He starts beating himself up.
Wilson is angry when he finds House soaking in his tub. At the hospital, the PPH team watches the video of Daryl's outburst. There is nothing wrong with his brain. House thinks it is "roid rage" from steroid use, but the ER tested for it and he is clean. Daryl injects his sore ankles with lidocane for every game. Foreman wonders if repeated head trauma could damage the base of the brain, leading to the pituitary gland. This could create excess hormones to cause the rage. House calls for a test of elevated GNRH in the blood.
As Taub administers the pituitary test, Daryl's mother insists that her son be able to play Saturday's game because there will be scouts there.
Meanwhile, House examines a soldier who is being redeployed to the war front after his contract has ended. The man is expecting a baby and doesn't want to go. Seeing the limp, he assumes House is a veteran who would understand. Yet House has no sympathy, and advises him to flee to Canada or shoot himself in the foot like they did during the Vietnam War.
Taub finds that Daryl's pituitary is normal but the GNRH is high, meaning that House was correct about the steroid use. When confronted, Daryl denies this and his heart rate increases. When his heart returns to normal, they suspect that he might have a hypertrophic cardiomyopathy. House orders Daryl to be put on a treadmill to stress his heart.
Foreman finds his brother Marcus in House's office. Although Marcus has just been released from prison, House has hired him as an assistant. Foreman says that House just wants to upset him. Foreman doesn't want Marcus to work there.
Wilson enters his bathroom to find an angry opossum in the bathtub. He accuses House of doing this in retaliation. House denies it. Wilson questions his intentions when hiring Marcus and wonders if House is secretly being kind. Chase interrupts to tell House that the treadmill did not induce Daryl's heart problem. House will do it with an injection of a vasodilator.
Daryl is packing up to leave the hospital. House notices that his hands are turning white. Taub explains that Raynaud's Phenomenon will cut vasospasms off the blood supply to fingers. Thirteen suggests arterial clots. Chase offers Takayasu's arteritis, but Foreman thinks Lymphoma is a better fit. House orders an ethanol drip to test for both. If Daryl becomes itchy, it is Lymphoma and they can remove his spleen. Yet it is Takayasu's, he will lose his radial pulse and Chase can start him on steroids. Marcus is sent to join Foreman and Thirteen to spy for House.
Cuddy informs House that there is a patient asking for him in the clinic. It is the soldier and he has shot himself in the foot. House tells him that that this will not get him discharged. Later, House decides to take a bath in Wilson's tub. When he gets up from it, the hand rail he had installed pulls out from the wall and House falls back. He waits for Wilson to get home and tells him that this means war.
Daryl becomes itchy, so Foreman concludes that he has Lymphoma. Chase is removing Daryl's spleen in the Operating Room when he shows Foreman that the liver is inflamed. They were wrong about Lymphoma. Foreman tells the team about their mistake, and that the patient might possibly have Polymyositis. Taub adds that Daryl could have picked up viral hepatitis in the locker room.
House grills Marcus for scoop on Foreman. Marcus says that they were arrested as teens for stealing a car. Foreman was fast with a flathead screwdriver. Just then, Foreman approaches to inform House that Daryl's blood is clotting. With football practice out in the cold, he must have cryoglobulinemia. Marcus continues his story and says that Foreman never wanted to disappoint their mother ever again. House is surprised to learn that their mother recently died. Foreman did not tell anyone. House goes to Wilson, knowing that he was not the one to unscrew the bathtub rail because they only own a Phillips head screwdriver. The rail uses flat screws. They realize that someone else is messing with them in the condo.
As Foreman informs the patient about thinning his blood out, Daryl's mother urges him to hold off treatment until after the Saturday game. Foreman finds Daryl preparing to leave the hospital once again, determined to play football.
House and Wilson are up all night, waiting for the intruder. They bicker as the fire sprinklers overhead turn on and soak the apartment. Wilson concedes that House would have never jeopardized his flat screen TV for a prank. Imitating a French sleuth from a mystery novel, House calls the team, Marcus and Cuddy together to see if one of them is the intruder. He thinks it is Foreman and tells the group that his mother had died. Marcus gets angry and quits.
House tends to the soldier, whose toe has become gangrenous. He is willing to sacrifice the toe, but House informs him that the Army will still take him. Meanwhile, Foreman accompanies Daryl to the football stadium, trying to convince him to not play. Suddenly, Daryl stops and asks to return to the hospital because he cannot see.
Foreman visits his brother at a halfway house and tells the team on the phone that he put nitrates in Daryl's water to stop him from playing. He doesn't want him to die on the field. House notices that Daryl did not lose much weight while in the hospital. Someone his size should have dropped at least ten pounds. Even though Daryl is not taking steroids, Chase thinks his body is producing antibodies to combat cancer. This is called paraneoplasitc syndrome. Foreman offers Marcus his place to live.
In the cafeteria, House takes a spill on the ground. Lucas is responsible for tripping him. He boasts that he has been the one breaking-in to the condo in retaliation.
The team cannot locate any sign of the patient's cancer. House realizes that Daryl's dark skin is masking melanoma, and House finds a spot of it on the foot. He will be all right, but Daryl is at a loss what to make of himself after missing his scouting game.
Lucas comes to get Cuddy in her office. She mentions that Wilson and House have been the victims of a prank, knowing that it really was Lucas doing it on her behalf.
Wilson notes that House provoked Marcus to quit. House thinks they shouldn't try to get revenge at Lucas. He watches as the soldier he treated is wheeled out. The man's entire foot has been amputated. He did it in order to not return to war.