The Thirteenth Chair

In Calcutta, Inspector Marney and Commissioner Grimshaw approach Leonard Lee's bungalow, setting the stage for the case. They assess the victim's reputation and prepare to question suspects as the investigation begins.

John Wales volunteers to organize a séance inside the supposedly locked house to pressure suspects. The plan relies on darkness and psychological pressure rather than stage tricks. This experimental approach signals that the night will uncover hidden tensions.

The Governor, Sir Roscoe Crosby, his wife, their daughter Helen, and other household members gather to participate in the séance. Grimshaw arranges the meeting, with Wales guiding the proceedings as organizer.

Mme. Rosalie La Grange performs demonstrations and then assures the participants there will be no trickery tonight. She appears grandmotherly and reassuring. Her cryptic talk with Nell hints at deeper connections beneath the surface.

Doors and windows are locked as thirteen sit in a circle. The lights go out and the participants clasp hands around La Grange while her and Wales' voices fill the room. The tension builds as the evening unfolds.

When the lights come on, Wales is found dead in his chair, stabbed through the heart. Inspector Marney seals the scene and states that someone in the room killed Lee and possibly Wales. The knife used to kill Wales remains missing.

Mason discovers Nell's handkerchief on the floor and blood is detected. The missing knife heightens suspicion directed at Nell and others in the circle.

Nell admits La Grange is her mother, but the Crosby family claims to accept it. Nell explains she visited Lee to retrieve Helen's love letters, while Helen denies this claim, complicating alibis.

Marney contemplates arresting Nell for her visit and the bloodied handkerchief. La Grange pleads for time to obtain a true message from the dead.

La Grange points to a knife embedded in the ceiling as a supposed message from the departed. The Inspector urges everyone to be mindful of hand movements as the investigation tightens.

A reenactment has Wales's body propped in the chair and the rules are reiterated. In the dark, Nell cries that Wales is moving as the lights reveal his upraised arm pointing toward the ceiling knife. Clues accumulate: Mason's clean hands, Dick's lampblack-stained hand, and the mother's stained hands become key indicators.

The killer is revealed: Mason killed Wales and manipulated the circle, having kept out of the circle when needed. The bloodstained evidence and hands provide the final proof, and the Inspector notes that Wales never suspected Mason.