A young faith healer, Boyd, is giving a service and "heals" a woman, allowing her to walk as his father Walter looks on. But as Boyd leads the congregation he has a series of spasms and collapse to the ground.
House shows up for work and Wilson tries to collect his stuff, but he's also peeved that House doesn't want him at his weekly poker party. Meanwhile Cameron and Foreman are giving Boyd tests and he claims to talk to God and knows about Cameron's ongoing feud with Foreman. The tests show low sodium and diluted urine, and House is skeptical of Boyd's religious beliefs and God in general. House orders preliminary treatment and goes to talk to Boyd and finds him lucid, then notices he's drinking water from a previously opened bottle.
Wilson is meeting with a cancer patient, Grace, who wants to go off of her pain medicine. House interrupts for a consult to basically confirm his own theory and rant about God. Boyd wakes up and starts walking through the halls, singing hymns. He walks up to a water fountain and sings out, then vaguely recovers. As Chase leads him back to his bed, Boyd sees Grace, knows she's sick, and lays hands upon her.
The staff conducts a new meeting and House goes with a MRI when Wilson barges in and is upset that Grace is feeling better but she'll crash when she realizes she hasn't been cured. Chase chats with Boyd while Foreman and Cameron have a chat about religion and Cameron is dismissive of Foreman's attempts to be friendly. Later Boyd comes in to talk with House who accuses him of playing with people and Boyd talks about what God has said to him about House. He concludes by telling House that God wants him to invite Wilson to his poker game.
House confronts Wilson who denies he said anything to Boyd. The MRI shows an abnormal area showing tubular sclerosis and they prepare to operate – House believes the growth is responsible for Boyd's "symptoms." Wilson talks to Grace who has gained a hope for the future and Wilson tries to caution her. Foreman and Chase give Boyd and Walter the news and he refuses surgery. House asks Wilson to talk to Boyd and Wilson agrees if House will let him into his poker game. House does so and Wilson convinces Boyd that if he's truly a saint then his humility would let him agree to the tests.
At his house that night, House is playing the piano when Wilson comes in and reveals that the tests show Grace's tumor has shrunk. House demands all of her records and orders her to be kept away from Boyd – she does so anyway. House realizes the only way Boyd will agree to the surgery if they can prove Grace is dying and Boyd didn't heal her. The staff now tries to diagnose her cure and check out her home while House orders Boyd to stay for 24 hours.
Wilson shows up at the poker game and they play while House provides guidance to his team over the phone, interrupting his winning streak. At her house, Chase finds that Grace has a boyfriend and slips out just ahead of her boyfriend returning. House figures that Grace told Boyd about the poker game when she learned it from Wilson, who is her boyfriend.
Boyd is preparing to check out with his father's permission while Wilson storms out after accusing House of hating religion because he always has to know the rules and be in control. They're interrupted by a call – Boyd is running a fever. It's back to differential diagnosis and House concludes the tubular sclerosis isn't responsible and it's time for a lumbar puncture but Boyd refuses man's treatment. They appeal to Walter but he prefers to leave it in God's hands.
House gets Wilson to intervene but then figures out that Boyd had a herpes virus which he got from sex and gave to Grace which attacked her tumor and caused it to go into temporary remission. House finally gets Walter to order Boyd to undress and they find the tell-tale sore.
Later Boyd meets with House and wishes him good luck with his life of certainty. Grace is still happy even though the cancer is coming back. And House and Wilson are good.