Molly Murphy Sullivan's husband Daniel, a police captain in turn-of-the-century New York City, is in a precarious position. The new police commissioner wants him off the force altogether. So Daniel accepts an assignment from John Wilkie, head of the secret service. Molly believes her husband is in Washington, working for the president, until she spots him in San Francisco during a movie news segment. Then she receives a strange letter from him, leading her to conclude that he wants her to join him in San Francisco.

She takes her young son Liam on the cross-country train trip, but when they arrive in San Francisco, Molly is told that she's too late, her husband's funeral was yesterday. She's devastated, even more so when she receives a cryptic note saying Daniel's death was not an accident. In her grief she stays on to investigate, until she meets a strange man at a party, whom she soon starts to suspect may not be quite who he appears. Then Molly finds another body in the basement, but before she can report it, the Great Earthquake strikes San Francisco, and the servant runs off in a panic with Molly's son. Suddenly Molly has no idea where to turn or whom to trust, and she knows there are many lives on the line, including her own.