When a transcontinental airplane is forced to land in the desert in a thick fog, the crew and ten passengers find refuge in a deserted house, where they start up an electric generator and turn on the lights. After the lights go out unexpectedly, one of the passengers is killed. Another passenger, a detective, claims he was guarding the deceased, who was carrying valuable diamonds, which are then discovered to be paste. Later, another person is murdered. Eventually, the murderer is found in the guise of a clergyman.