When Laura goes to her appointment and finds Martin isn't home, she stays but hears a noise in Martin's underwater basement. She finds the broken mask and thinks Martin is the killer. An attempt to call Eric fails when he is still unconscious. When he awakens, the nurse tells him of Laura and both he and Vermeer head to Martin's house. Martin arrives and waits for Laura only to hear a sound in his basement. Laura confronts him and hits him repeatedly with an oar. However, the killer comes out of the water and grabs Laura. Eric arrives in time and shoots the killer. Martin finally confesses that the killer is a childhood friend of him and fellow diver who was shunned by society after a commercial diving job caused him to be disfigured by uranium hexafluoride poisoning. The killer arrives at his home, where he reveals himself and decides to take his own life before the police arrive.