While Peggy is entertaining three callers the light goes out. One of them takes advantage of the darkness and steals a kiss. Peggy indignantly leaves the room, with a fraternal pin as the only clue she has to the culprit which she finds in the lace of her waist. This, however, is not much of a clue, as all of the boys belong to the same frat. Peggy writes to each of the boys, who are roommates, and tells them that she must have the truth. As a means to get into their old footing with the girl, each one of the boys confesses to the crime. Bob is the first one to confess and Peggy sweetly forgives him. Then when Cort shows up with a confession, Peggy sends him from her in disgrace. Later the doctor calls to confess and be finds that Peggy has the mumps, so for a while he has the inside road. As soon as she is well, Peggy dismisses the doctor and decides to go to the boys' rooming place and see if she can discover to whom the pin belongs. Here she finds that Cort is sick in bed with mumps. The mystery is solved to Peggy's satisfaction, for Cort has been the one she has loved all along.
—Moving Picture World synopsis