Plot

The apparent hanging of a suicidal student is revealed to be murder, as he was already dead when the noose was placed around his neck, killed by a sharp needle that penetrated the back of his skull with great force.

Ken Harris, a student at a New England college, welcomes the visit of his father Joseph to the campus. Returning to his dorm, Ken finds that his roommate Byron "By" Coates, the brother of Ken's girl friend Jean, has locked him out. Staying the night in the room of his friend Charlie Fenlon, Ken is horrified to be awakened by the knocking of By's body swinging outside the window. Although By apparently hanged himself, the autopsy reveals that he was killed by a needle shot into the base of his brain. Joseph takes over the investigation on behalf of the college because of his reputation as an amateur criminologist. At a gathering of the students, the murder is announced and, just as he is about to offer fresh evidence, Sam Anderson is killed in the same manner as By. Joseph interrogates Professor Bostwick, then Jean and her companion, Miss Case, and discovers that By was about to turn twenty-one and receive a large inheritance. John Mesero, a student from France, offers his condolences despite having been an enemy of By because of their mutual resemblance. While talking with By's mother, Ken wonders about a picture of his father in her photo album. Ken then accidentally discovers the letter By had received from his mother the night of his death. The message explains the inheritance and identifies John as By's disinherited half-brother from Mrs. Coates's first marriage. While reading, Jean is shot at by a cloaked figure. The man turns out to be John, who admits killing Sam, but is shot in the back before he can name By's murderer. Arriving at the college, Mrs. Coates abruptly identifies Bostwick as the mysterious "Joe," the husband who abandoned her and their son John. Joseph explains that Bostwick had planned to kill By and Jean, then claim their entire inheritance through John. Jean now agrees to Ken's proposal of marriage.