Psychic Nan and Medium Sarah have been agents of Lord Alderscroft, the Elemental Fire Master, since leaving school. Now, Lord Alderscroft assigns them another commission: to assist the famous man living at 221 Baker Street, Dr. John Watson and his wife. Their assigned task divides the girls for the first time since they were children. A German opera star begs Sarah for help, seeking a Medium's aid against some spitirs. As Sarah becomes entwined with the Prima Donna, Nan continues to assist John and Mary Watson, only to discover that Sarah's case is far more sinister than it seems