Growing up, Kate Priddy was always a bit neurotic, experiencing momentary bouts of anxiety that exploded into full-blown panic attacks after an ex-boyfriend kidnapped her and nearly ended her life. When Corbin Dell, a distant cousin in Boston, suggests the two temporarily swap apartments, Kate, an art student in London, agrees, hoping that time away in a new place will help her overcome the recent wreckage of her life. Soon after her arrival at Corbin’s grand apartment on Beacon Hill, Kate makes a shocking discovery: his next-door neighbor, a young woman named Audrey Marshall, has been murdered. When the police question her about Corbin, a shaken Kate has few answers, and many questions of her own—curiosity that intensifies when she meets Alan Cherney, a handsome, quiet tenant who lives across the courtyard, in the apartment facing Audrey’s. Alan saw Corbin surreptitiously come and go from Audrey’s place, yet he’s denied knowing her. Then, Kate runs into a tearful man claiming to be the dead woman’s old boyfriend, who insists Corbin did the deed the night that he left for London.