My heart just aches for this film. The Unknown comes from director Henry Levin, with a screenplay by Charles O'Neal and Dwight Babcock based on a radio play by Malcolm Boylan and Julian Harmon. It features Karen Morley, Jim Bannon, and Jeff Donnell in the leading roles; Alexander Steinert handled the music, and Henry Freulich was responsible for the cinematography. It’s such a delightful, classic spooky house mystery about a group of family members who gather at a large estate for a will reading. Not long after they arrive, odd events and accidents begin to happen throughout the evening. Running only seventy minutes, Levin's film moves quickly and avoids unnecessary distractions. The familiar tropes of a haunted house are present here; shadows play a significant role in the visuals—Freulich’s photography is particularly noteworthy—creating an unsettling feeling as the characters explore hidden passages, dimly lit hallways, a foreboding staircase, and even a mausoleum located nearby. The audio design contributes significantly because it includes things like creaks, groans, and the disturbing sound of a child crying at night—all executed perfectly. The people in the story are an interesting mix of oddballs, potential suspects, determined investigators, and a charming woman. The mystery itself remains engaging throughout, and although the ending isn’t entirely unexpected, it provides a satisfying conclusion to a pleasant viewing experience. It earns a 6.5/10.

Source on TMDB