On a wintry November morning, both the Prime Minister in Downing Street and the U.S. Ambassador in Grosvenor Square receive an appalling ultimatum - a nuclear device, concealed somewhere in London, will be detonated within 72 hours unless the British and United States governments accede unequivocally to the demand for an independent Palestine. With chilling plausibility, Antony Trew describes how a group of ultra-militant terrorists - disavowed by Yassir Arafat and the PLO - hi-jack a nuclear warhead, smuggle it into London, issue the ultimatum, and so trigger off a macabre treasure hunt which has the lives of hundreds of thousands of Londoners at stake. There is grim reality in the account of Cabinet discussions in Downing Street, of hot-line consultations between heads of state, of desperate efforts by security services and secret agents to trace the warhead - all against a background of sustained suspense and mounting tension as information trickles in and the minutes tick away towards the dramatic climax.