There is a good story here but it makes for such an unexciting and times clunky old fashioned film.
Chief Inspector Gerald Harvey visits mystery novelist Paul Temple (Anthony Hulme) at his country mansion. He wants Temple's help over a spate of jewellery robberies. The gang are not afraid to kill. At the nearby local pub where Temple drops him off, Harvey supposedly shoots himself suddenly. The landlord tells Temple it is suicide and this is confirmed by the local doctor. Temple has doubts.
Temple hooks up with journalist Steve, it was her brother that was killed. The gang carried out similar style of robberies in South Africa. It seems the same gang has come over to Britain.
Then there is the meek Amelia Marchment who is studying the history of English inns who seems to know something about the gang as well.
Based on the Francis Durbridge radio thriller. There is a kernel of a decent mystery here with a criminal mastermind behind it all and lots of double crossings. However the film is too low budget, Hulme is too plain and the film production company just cannot realise this as an effective thriller.