In the heart of the swamps, in solitude, Rosamund Morley lives with her father and sister Jennifer. An unexpected meeting with the gloomy and mysterious Swamp Tiger - Michael Bradshaw becomes a turning point in her life: she develops a deep feeling for him. After making sure that it is mutual, the lovers decide to get married. However, the sudden disappearance of Michael's little daughter Susan, followed by a series of strange and frightening events, interfere with the implementation of their plans. Only then does the Swamp Tiger decide to reveal his secret to the girl...