Set in a tenement boarding house, a lonely confirmed bachelor occupies a room across the hall from a dour spinster. Children run amok in the hallways playing pranks. Believing the bachelor perpetrated one particular prank, the spinster woman enters his room to confront him. She is followed by a neighbor child. Meanwhile, the other children have stolen a scarlet fever quarantine sign and posted it on the bachelor's door. The police, unaware that the quarentine sign is a prank, enforce the confinement. But aided by the sweet disposition of the toddler quarantined with them, the icy relations between spinster and bachelor begin to thaw, . . .