Kerstin is caught up in a murderous bank robbery by two Russians, but a third man's participation proves puzzling.

The A Unit investigation suggests a Cold War connection. Past secrets worth killing for are revealed as team members pursue the elusive men behind the crime.

A woman is found collapsed in the street, having escaped from an unknown basement. She has no idea why she was kidnapped and, with nothing else to go on, 'A' Unit follows a lead found in the basement to a drugs ring run by two brothers.

Investigating a series of murders and kidnaps, 'A' Unit begins to suspect they are linked to a shared high school experience - but this still isn't getting them any closer to catching the killer. Paul is investigating the sudden and mysterious death of his new-found friend from the security service.