Botanist Wilfred Glendon (Henry Hull) is in Tibet searching for a rare flower that only blooms by moonlight when he's attacked by a strange howling creature. After surviving the attack, Glendon travels back to London. But when the city is besieged by a series of werewolf attacks, Glendon learns the awful truth: He's the werewolf! The only thing that can cure his affliction is the rare Tibetan flower in this horror classic from Stuart Walker.