When a nun comes into the clinic with swollen arms, rash, and bleeding in her palms, Dr. House's diagnosis is a bad allergy, not stigmata as she believes. House gives her an antihistamine which appears to set off an allergic attack. However, when the nun gets tachycardia from the epinephrine House gives her to treat it, Cuddy concludes he gave her ten times the appropriate dose. When House insists he gave her the proper dose, Cuddy gives him 24 hours to prove the nun has another condition before she calls the malpractice lawyers. Although House finally vindicates himself, the answer doesn't help the patient. As her condition worsens, her fellow sisters pray for her while House and his team work to discover the cause of her illness. House wonders if he misdiagnosed her situation, not realizing that her past is coming back to haunt her.