The Token by Gerald Verner
Four murders in just over a month, and not the ghost of a clue as to who has committed them.
Except that in each case a little silver bell was left on the body of the victim. Under pressure from all quarters, Detective-Inspector Shadgold seeks the help of his friend Trevor Lowe, the famous criminologist. But Lowe has nothing to go on either. Until he is approached by terrified film star Gloria Swayne, who reveals that the first victim of the silver bell killer had been her secret fiancée…
Gerald Verner (1897-1980) was the pseudonym of British writer John Robert Stuart Pringle. Born in London, Verner wrote more than 120 novels that have been translated in over 35 languages, and many of his books have been adapted into films, radio serials and stage plays. Verner also wrote forty-four Sexton Blake tales.