Enigmatic fortune-teller Toby Knight visits 221B Baker Street seeking help with a sinister dilemma. Holmes, a staunch sceptic of all things mystical, dismisses Knight as a charlatan who preys on the gullible and demands that Knight leave immediately

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Watson, moved by the fortune-teller's distress, asks him to stay and reveal more about the issue concerning him.

Knight does so, confessing that some of his predictions have been eerily accurate, but with disastrous consequences for his clients, who then blamed Knight for their misfortunes.

Despite his misgivings, Holmes is intrigued by the details given by Knight and agrees to investigate the matter.

As the case unfolds, it becomes clear that someone is sabotaging Knight's livelihood, and that more than one person would like to see Knight fail. But who?

Holmes' sharp mind soon uncovers deceit and misdirection, which leads him to wonder if the prime suspect might just be the victim himself.