Mary (Aline MacMahon), an elderly woman with good intentions, takes pity on Henry (Basil Rathbone), an artist with no home. What begins as a simple offer to come inside from the cold for tea gradually turns into more. Before the unsuspecting woman knows it, Henry has convinced Mary to pay for doctor visits. It spirals out of control when Henry, his family and friends con their way into her home. Eventually, Mary creates a ruse to rid herself of the parasites, but they have a different plan.