The Spider plot
An ex-cop, now a private detective, is hired by a woman as an intermediary between her and her partner. Following the information about an important letter, the private detective invites this partner to his apartment to receive this letter, if someone else sneaks into his apartment. While the detective is in another room, the woman is murdered. Fearing false accusations, the detective takes the woman to her own flat, but the police find out and he is still suspected. He must find out the culprit and motive before the police arrest him.