Maurice Pogue has retrograde amnesia, a form of amnesia that prevents him from remembering anything that happened to him the day before. He realizes from a recording he made for himself the previous night (Sunday) – to keep himself in the know – that he's a private investigator in Los Angeles, and acquired the condition after being injured during a case. Pogue tells himself not to reveal his condition to anyone, as he's the key witness in the case against the man responsible for his amnesia. Appearing on the recording is a strange woman, Sarah Novak, who informs him she has been living under the alias Beth Holly in San Francisco, and she has come to L.A. because she is being blackmailed. The police then come to Pogue's office, and take him to what turns out to be his birthday party. He tells his friend Dolby that he's seen Sarah, and learns from Dolby that Sarah is dead. While at the party, Pogue also meets Anthony Doover, his doctor – the only person who knows of Pogue's condition.