In the Next Room (1930)
In The Next Room (1930) is an all-talking mystery film released by First National Pictures, a subsidiary of Warner Bros. and directed by Edward F. Cline. The movie stars Jack Mulhall and Alice Day. The film was based on the play by Eleanor Belmont and Harriet Ford, which itself was derived from the book The Mystery of the Boule Cabinet by Burton E. Stevenson.
More at Wikipedia.