The MHU are sent to Edinburgh to investigate the death of a recently released prisoner whose body is pulled out of the Forth River, imprisoned in a dog cage.

Annika reflects on 1984 when the team investigate the death of a man found in a block of ice on the Hebridean islands.

When Morgan starts working at a remote Scottish eco-resort, Annika's trip to visit her is interrupted when a local builder employed by the resort turns up dead in a nearby stream.

A brutal murder on Glasgow's canals hits close to home when the victim is identified as a former police officer.