Berkoff manages to destroy a UFO in the climax. In Destruction a battleship is the target of UFOs but Straker does not know why. Berkoff almost becomes victim to a laser beam sent from earth to the alien craft. Berkoff in the episode Deadline . Aliens are found dumped and organs removed.
Body snatchers are at work.
Called Quinn , the last but one episode ever. Berkoff is an evil doctor in a mental asylum. One patient, former agent Quinn, hallucinates and sees enemy soldiers and spies everywhere. A reworking of The Manchurian Candidate, Berkoff is of course shot down at the end. Berkoff has a small part in The Gravediggers from the Avengers with Patrick Macnee and Emma Peel.