The first series of this brilliantly compelling crime drama was one of the TV highlights of 2015, as viewers were left on the edge of their seats working out which one of a disparate group of suspects had committed a murder almost 40 years before.

Now, dogged cops Cassie (Nicola Walker) and Sunny (Sanjeev Bhaskar) are back with another equally twisty-turny case after a decomposed body is discovered inside a suitcase, in the River Lea in London.

But how are a nurse (Rosie Cavaliero), a police officer (Lorraine Ashbourne), a lawyer (Mark Bonnar) and a teacher (Badria Timimi) connected to the dead man, who went missing back in 1990?