Roger Dunn is the head of the CID division in Kent, and as a bank robber- murderer faces conviction, young Peter Dunn is kidnapped in order to swing the sentence. A handkerchief (with a laundry mark) and cigarettes (from saliva- blood groups can be typed) are all, that Dunn has to go on in a choice between his career and his boy; these bring him within the general area of the kidnappers, while Peter slips him an unnoticed to his whereabouts. Split-second synchronization here for a story which features the teamwork and laboratory techniques (authentic) which have replaced the olmesian mastermind and Jeffries' story for youngsters provides intelligent intelligence in action.