A Londoner returns from a South Seas fortune-hunting expedition minus his son-in-law who suffered a tragic end. A nervous wreck, the man screams around the clock about "the third day" and a man named "Mungahra." Mungahra was the expedition's native guide who, before dying, placed a curse on the greedy, self-serving Englishman who treated him like a savage.
Monica is a lonely young girl who is schooled at home by her Uncle Stephen and his housekeeper. When Monica talks about her new playmates Mary and Elsie, her Uncle believes she is just imagining things. He grows more concerned when he himself begins to hear Monica's playmates throughout the house.