It all begins when a prostitute is found floating upside down in Helsinki Harbour - a low-priority job that gets passed back to Hella. It's beginning to look like a serial killer is at work when another woman narrowly escapes being driven into the harbour, handcuffed to the car by her client. What begins like a taut whodunit turns into something more tantalising as Hella turns her attention to different suspects, often to the consternation of the fascinating Inspector Mustonen, charismatic, ambitious and trying desperately to live up to the standards of his wife.