Mackenzie Ottenberger, known as Otter to her friends, is a young engineer at a manufacturing plant in Phoenix Arizona. The shop is busy and Otter has a lot on her plate until Clark, the company salesman commits suicide. Suddenly she finds herself in the middle of the investigation, sure that Clark would never kill himself. Soon a mysterious suitor appears, clues are dropped off on her front porch and the police are poking at her home security. With the help of her best friend and housemate Tempest, her boss Michael and a the adopted nephew of the deceased, Otter puts together the evidence and finds that nothing is as it seems. Can a working knowledge of science and math help her catch a killer or will it be something from her past that saves her life?