Captain Gregson calls Sherlock in to discuss a homicide. Maria Gutierez disappeared three year ago and her remains have been found. The visiting detectives question Sherlock and he realizes this is not an consultation but an interrogation.
A note from Sherlock, arranging a meeting, was found on her body.
Sherlock has no recollection of the woman but during that time, he was using drugs heavily. Joan promises to help him. Sherlock meets with his old dealer, Oscar, who doesn't remember Maria.
On his way back home, Sherlock is attacked by two men. He steals one of their wallets, which belongs to Prentice Gutierez, Maria's brother. Sherlock and Joan confront him. He tells them that Maria was being harassed at one of the offices she cleaned, Councilman Barclay's.
Joan and Sherlock meet with the Councilman. He admits his Press Secretary was harassing Maria, but he was out of state when she disappeared.
Detective Bell gets a list of people that Maria knew from the soup kitchen where she volunteered. Sherlock recognizes one of the names, his old dealer, Oscar. He confronts Oscar who claims Sherlock killed Maria.
Joan says it's not possible, but Sherlock counters that she did know the old Sherlock.
Sherlock is arrested after a witness comes forward and says he overheard Sherlock threaten to kill Maria.
Joan goes to see Oscar. He gives some bloody clothes he discovered in Sherlock's home after Maria disappeared.
Joan meets with Sherlock. The clothes were the wrong size. They speculate that Maria witnessed a murder and took the bloody clothes and gave them to Sherlock. He still doesn't remember Maria, but he does recognize the shirt.
Joan, Gregson and Bell meet with Councilman Barclay. He was having an affair with Kelsey Prior who was killed a couple days prior to Maria's disappearance. Maria saw him throw away the bloody clothes and took them. He lured her out of the safe hotel Sherlock put her in and killed her.
Sherlock tells Oscar that he arranged for a standing reservation at rehab for him. Oscar says Sherlock will need him (and drugs) again.