The Invisible Foe.

Mary and Billy are sweethearts. Mr. Stanley, the girl's father, suspects the boy of being a victim of the drug habit. Billy, in an attempt to master his craving, abstains from the drug. He is invited to dinner at his sweetheart's home. Stanley notices the boy's nervousness. He resolves to call upon him at his office and learn the truth. The next day, Billy's desire for the drug becomes so intense that the moment his employees leave the office, he brings out his hypodermic.