When a boat carrying illegal passengers is found crashed in the Thames, the team investigate.

The team follows the trail of the people traffickers, and has to find any remaining survivors before a highly contagious disease breaks.

The team investigates a hit-and-run accident, an arson and a woman who collapsed on her hen night.

The team investigate a man who died on a night bus, an office prank gone tragically wrong and the suicide of a pro footballer.

Harry and Nikki's friendship is rocked by the discovery of the body of Harry's ex-lover.

Memories of his own daughter's death are stirred up when Leo is called in to investigate the apparent suicide of a teenage girl.

When a third killing takes place on school grounds, Leo races to find some connection between the apparently motiveless murders.

Harry and Nikki are drawn into a war between a medical research establishment and a group determined to take direct action.

With Nikki missing, Harry works against the clock to find out who is responsible for the murders and finds himself in a cover-up.