Madame Sosostris was a skilled hypnotist and a self-proclaimed clairvoyant.
She was involved with black mass ceremonies during the late 19th century. Unlike mediums of that time who said they used Red Indian spirit guides to contact the dead, Sosostris said she used devils and demons. She was associated with Baron Maupertuis. (PROSE: All-Consuming Fire)
Sosostris performed a hypnotism act at the New Regency Theatre for Henry Gordon Jago. She helped to break the Master's hypnotic spell over Percival Quick. She was being assisted by "Nocturne" who was actually the Sixth Doctor in disguise. She accompanied Jago and George Litefoot to the Master's lair. (AUDIO: Masterpiece)