"Quick Curtain" by Alan Melville is another long-lost Golden Age detective novel republished by the British Library. Alan Melville is better known as a broadcaster and playwright but he also wrote a number of novels including crime stories in the 1930s. The theatre is where this book is set, the murder taking place during a performance where the fake bullet in a stage shooting is switched for a real one.
Inspector Wilson is set to solve the case with the help of hid adventurous and frequently scolded son. The book is a witty delight, not to be taken too seriously as a crime novel but works much better when you accept this is more a satire on showbusiness.
That is not to say the book hasn't got a decent plot and some interesting sleuthing. Credulity is stretched a bit far though but you don't mind because of the enjoyable way the story has been put together.