The Moonstone is an adaptation of the 1868 novel of the same name by Wikie Collins which is regarded as the first detective novel.
Now this is a pure Golden Age mystery: a country house with a motley collection of stereotypes, a mysterious crime is committed during a storm and it even has a touch of the Orient with a supposedly cursed jewel from India.
Ann (Phyllis Barry) is the owner of the stone, highly valuable and various people at the house including the money lender Von Lucker (Gustav von Seyffertitz) and the failed businessman Godfrey (Jameson Thomas) have various motives for stealing the stone which goes missing one night. Luckily a Scotland Yard detective (Charles Irwin) is on hand to try and unravel what is going on.
A lovely whodunit set in a gloomy country house in Yorkshire. The crime method is rather odd and the film chops about a bit but has plenty of atmosphere.