Plot synopsis: A huge train accident in an idyllic small town shocks the whole of Finland, and accident investigator Marita Kaila is faced with the most difficult case of her career. Under increasing pressure, Marita and her team try to find out what led to the death of dozens of people. But there is also a tragedy in Marita's own past, which the demanding investigation brings to the fore. Will he solve the case before the pressure becomes too much?