Librarian Charlie Harris and his ever-intuitive feline friend Diesel must catch a killer in a deadly game of cat and mouse where no one is who they seem to be...

At last, Charlie and Helen Louise's wedding is only a month away. They're busy preparing for the big day, and the last thing Charlie needs is a new mystery to solve. Enter Tara Martin, a shy, peculiar woman who has recently started working part-time at Helen Louise's bistro and helping Charlie in the archive. Tara isn't exactly friendly and she has an angry outburst at the library that leaves Charlie baffled. And then she abruptly leaves a catered housewarming party Charlie's son Sean is throwing to celebrate his new home in the middle of her work shift. Before ducking out of the party, Tara looked terrified and Charlie wonders if she's deliberately trying to escape notice. Is she hiding from someone?

When Tara is viciously attacked and lands in the hospital, Charlie knows his instincts were correct: Tara was in trouble and someone was after her. With the help of his much beloved cat, Diesel, Charlie digs deeper, and discovers shocking glimpses into Tara's past that they could never have predicted. Will they catch the villain before Charlie's own happily ever after with Helen Louise is ruined?