When Sean Legg, the island's Chief Minister is kidnapped, only a select few are made aware. Sean soon discovers that his captors are Islamic fundamentalists who plan to set up a terrorist training camp on the island.
Police constable Sarah Flemons and her dive buddy Penny Lomax, are enjoying an evening dive round the rocks of Peel Castle. They discover the entrance to a cave where they are met by another diver. Only Sarah survives the encounter, but she is taken captive in the same huge cavern under the rock where they are holding Sean.
Clemence Quirk and Elinore Kinrade, along with their black Labrador, Millie spot unusual activity within the castle grounds. Clem and Eli are not the sort of youngsters to let a thing like that pass. So when the dynamic duo discover an underground passage, their natural curiosity gets the better of them. That's when they stumble across their Chief Minister.
Meanwhile, Ken Stafford, formerly in the SAS brings in some of his former regiment friends with a cunning plan to free Sean Legg. Unfortunately, Sean's father-in-law, Nick Ferris, known for being nimble of foot when the police draw near, also becomes involved. It's all a recipe for an unforeseen ending.