Margaret Semple (Sara Kestelman) is a high ranking civil servant in the Ministry of Defense, and a russian agent. She is defecting to the USSR on the instruction of her KGB handler and lover Gregori (George Irving). Her route of escape brings her to Jersey - and the attention of Bergerac (John Nettles). After a bungled midnight flit by boat an associate of Gregori's is accidentally killed by Semple. She becomes increasingly desperate, briefly taking Bergerac's girlfriend Francine (Cécile Paoli) hostage at gunpoint. Agents from MI6 descend on the Island and predictable friction with the local police ensues. It becomes obvious that Gregori does not have Semple's best interests at heart and has no intention of her leaving Jersey alive. Following her trail across Jersey, Bergerac arrives just in time to save her from Gregori - but not from the further attentions of MI6 and the authorities in London.