An isolated house is too remote for a lone servant, who leaves a note, quietly exits the back door, and puts the key under the mat. Left alone in the house is a mother and her infant. A tramp has watched the servant leave and begins to skulk. When the lady of the house sees him outside as he discovers the key, she's terrified and desperately phones her husband, who's at work in town. He jumps into a car that's idling in front of his office and races toward home, the car's owner, and police, in hot pursuit.