Worryingly for Scotland Yard, four officers disappear whilst on duty. One vanishes chasing a forger. Then two officers disappear searching for a wanted jewel thief in Hythe. Finally, a fourth officer vanishes in Hythe, after being sent to the nearby village of Stonehurst. Criminologist Trevor Lowe investigates a lead: someone has telephoned to arrange a meeting at the crossroads between the two villages. Lowe keeps the rendezvous but finds the man has been silenced - shot dead in a ditch...