Part 3 of 4 of the eerie thriller. The island is reeling from yet another murder, that of bird watcher Dr Symonds in his tent. But there are curious aspects of the case, not least traces of radiation at the scene of the crime, as well as an odd naval vessel found on the beach. Inspector Inskip is deeply suspicious of Colonel Howard, who offers to help in the hunt for the killer on the island, but Howard later receives a mysterious phone call. Meanwhile Fiona discovers Symonds' camera and realizes it may of captured his killer on film, but while she checks out the camera, at the Coastguard Station the killer stalks their next victim... Starring James Warwick, Celia Imrie, Maurice Roeves, James Cosmo, Tom Watson, Jonathan Newth, Jon Croft, Ronald Forfar, Jeff Stewart, Fraser Wilson, Tony Sibbald, Robert Vowles, David Gilpin, Julie La Rousse, John Oakden and Pat Gorman. Part 3 continues to be a puzzle, but the latest discoveries move this less into the mystery bracket and into something far more stranger. This episode is memorable for the attack on the Coastguard Station - could it actually be Nellie Boswell?