Green and Valentine find a body on the banks of the Thames. The victim, Michael Drummond, is a disgraced doctor under investigation by the General Medical Council. He appears to be involved in a death on duty, and is under fire from friends and family of the victim. One of the suspects, Dave Batchelor, reveals he lost his girlfriend at a party Drummond was at in the 90s. Green tries to get through to Dave, with no avail. Events escalate when a friend of Drummond's is found, with Dave holding a needle to his neck.