John Mannering was making his way to Hallen House, a lonely old country mansion, to purchase the famous Lake Emeralds from a man who called himself Silas Bellamy. But on his way across the moors, he meets two mysterious strangers who warn him that he will be in mortal danger if he continues with his journey. Though Mannering -- alias the Baron -- finds the house quite normal at first, he soon discovers that two young girls are imprisoned within its walls. What's more, those who visit can never leave!