Dexter is sent to investigate a blood-soaked crime scene, and is gripped by a suppressed memory. Meanwhile, Rita is charged with assaulting Paul and could lose the children in a custody battle. Angel investigates a hunch regarding the Ice Truck Killer.
When a key to a room at the Marina View Hotel is delivered inside a jar of blood to the Homicide Department, Sgt. James Doakes (Erik King) and Debra Morgan (Jennifer Carpenter) visit the hotel, where they find a room completely drenched in blood. Dexter is sent in first to investigate, but seeing the blood-covered room causes him to have an unexpected panic attack. He collapses and runs from the room. The forensics team surmises that the blood in the hotel room came from at least five different bodies, although none were in the room. Since there were only one set of footprints in the room, they assume that the victims were killed elsewhere and their blood spread around the room by the killer. Debra suggests that the Ice Truck Killer, who had five bloodless victims, may have been responsible.
Angel finds that he cannot stop talking about his divorce when trying to meet new women at a bar. After he meets a woman recovering from her own divorce, he leaves her to speak to a prostitute whom he sees across the room with a prosthetic hand and fingernails painted in the same way as the Ice Truck Killer's first victim. Working on a hunch that the Ice Truck Killer is an acrotomophiliac (an individual who expresses sexual interest in amputees), Angel decides to speak to Debra's boyfriend Rudy Cooper (Christian Camargo), a prosthetics specialist. Rudy cooperates with the interview but gives Angel no helpful clues, and Angel is later stabbed in a parking lot.
Rita finds out from a county sheriff that Paul, her abusive ex-husband who attacked her the night before, is pressing charges against her for assault. She talks with a lawyer, who tells her that since she invited Paul into her bedroom, she cannot prove that her intent was to defuse the situation. At a hearing, it is revealed that Rita violated her and Paul's custody agreement, making Paul's case against her even stronger. When Paul drops by Rita's house to return their children, he threatens Dexter when the two are alone in the kitchen, and Dexter responds by hitting him with a frying pan. Paul loses consciousness, so Dexter drives his body back to Paul's motel and frames him for drug abuse. Dexter alerts the police and Paul is sent back to prison.
With encouragement from Rudy, Dexter decides to dig up his repressed memory rather than avoid it. He returns to the bloody hotel room, where he relives the memory, which he realizes was of the murder of his mother, right in front of him when he was three-years-old.