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

The case becomes entangled in Annabelle's romantic relationships when Sam discovers her friend may have had an affair with a student.

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

The hunt is on for Mr Harris, but the murderer may be closer to home. Meanwhile, Sam grows closer to surgeon James Reynolds.

A tragic scene is discovered when a young mother apparently dies of an overdose. When another addict dies in an explosion, Sam has a bigger case on her hands.

Are the deaths linked to a drug war or is this the work of vigilantes? Sam suspects a personal tragedy is at the heart of things.

The death of a farmer involving a combine harvester seems like an accident - until Sam receives an anonymous tip-off.

Sam looks for connections between Ian Neal and a killing in Northern Ireland in 1985. Meanwhile DI Connor's wife arrives in Cambridge.