McCall helps a mob accountant, Bert Singer, scour the city for a lost ledger of evidence he must provide to the FBI in exchange for entrance into the Federal Witness Protection Program. Also, Mel frets over how to tell her best friend, who comforted her for years about Harry's death, that Harry never died at all.

McCall receives a desperate plea for help from her former CIA trainee, now a full-fledged agent, that leads her into a confrontation with Mason Quinn, the most dangerous enemy from her past in intelligence. In need of confidential information about the agent's latest assignment, McCall forms a tentative alliance with Carter Griffin, a by-the-book CIA handler.