A surprisingly engaging feature sees John Gregson as a detective ("Insp. Parnell") brought into investigate the kidnap of the son of the wealthy "Chester" (Alec Clunes). Interestingly the kidnapper "Marlow" (Robert Shaw) has locked the child into an attic room in an unknown London address then gone to the man's home to demand the ransom in person - so we know all the characters from the start. Midver mais...