This is a strange, antediluvian pleasantry (old-fashioned even in 1974), resembling nothing so much as one of those Francis Durbridge serials where everyone is a suspect, everyone has a secret and everyone lies like mad.
A businessman is shot, and suspicion falls on his 'friends' (all parasitical hangers-on), 'secretary' (mistress) and his estranged son (John Thaw, just prior to his Sweeney superstardom). A gritty detective (Glyn Owen) and an enigmatic MI5 man (Peter Sallis) investigate, and soon link the crime to the murders of various shady Chicago characters in the UK.
The suspects are slain at regular intervals, until the final unmasking of the villain and a somewhat perfunctory climax.
Made by Southern Television for the ITV Network.