The Boomerang.

Simon Watson, devoid of conscience, has become wealthy through the manufacture of "Watson's Remedy." One day he is stricken with terror when he finds a bottle of the medicine in the hands of his little child, Helen, and he warns her never to touch it. But the little one's curiosity is aroused and when her father has left for his office, she tastes the medicine and becomes violently ill. John Smith, a young workman, has a little daughter, Margaret, who is taken sick and the mother secures a bottle of the "remedy" at a drug store. Instead of relieving the child's pain, the medicine causes her to lose consciousness and when the horrified father learns the cause, he determines to seek Watson's life.