Sam must investigate a case with a painful personal connection when a close friend is murdered after the Cambridge May Ball.

A young woman is found dead in an empty house. Why was she there? Sam suspects another person was involved.

Two elderly brothers are found dead in their home, with no apparent injuries. A post mortem discovers suspicious puncture marks and a possible racist connection.

Sam is called in to identify the naked body of a woman uncovered on a ski slope in Norway.

Professor Leo Dalton and Dr Harry Cunningham join Sam Ryan in the investigation of a massive traffic accident in which not everything is as it seems.

Sam, Leo and Harry are at odds with the police investigators when a covert operation is exposed. But has Sam overstepped the mark this time?

The murder of a probation officer leads the team to the doorstep of a police cadet college, as they quickly establish a link to a similar murder just months before.

As the police investigate the possibility of a copycat killer among the students, a friend from the college pressures Sam to put loyalty above the truth as the case unfolds.

When his wife and teenage daughter are involved in a hit-and-run car crash, Leo begins a painful journey back to his native Sheffield.

As the police infiltrate a gang of identity thieves, Leo faces a choice between justice and revenge.