Nest Of Vipers is an episode of series 7 that first aired on 9 January 1992.
When two human skulls are found at a construction site, Taggart, Jardine and Reid are left to catch the killer. Poisonous snakes are left killing people with their bites. The killer is setting them on his victims. The skulls are later found stolen from the laboratory. They stole the wrong skulls so Jardine and Taggart have a good chance of catching the killer.