Tasha Mayo is a client of Strike and Robin. She hires the Agency to protect her from a stalker, as she didn’t think that the police were taking the matter seriously enough. Tasha explains to Robin that she had given the police a physical description of the stalker and told them where he lived. Tasha was appearing in a play near Shaftesbury Avenue. The stalker was always hanging around the stage door, and got nasty when she refused a  selfie. The agency establishes that the stalker is one of two brothers they nickname Frank One and Frank Two (Ch 13). 

The case of the two Franks becomes more complex as the detectives discover that both brothers are stalking Tasha, and the quest to catch them in the act becomes one of their more challenging sub-cases (Ch 32).