Victor Silvius has spent nine years as an inmate at The Grange, a private sanatorium, for the crime of attacking judge Sir Giles Drury. Now, the judge's wife, Lady Elspeth Drury, believes that Silvius is the one responsible for a series of threatening letters her husband has recently received. Eager to avoid the scandal that involving the local police would entail, Lady Elspeth seeks out retired stage magician Joseph Spector, whose discreet involvement in a case Sir Giles recently presided over greatly impressed her.
Meanwhile, Miss Caroline Silvius is disturbed after a recent visit to her brother Victor, convinced that he isn't safe at The Grange. Someone is trying to kill him and she suspects the judge, who has already made Silvius's life a living hell, may be behind it. Caroline hires Inspector George Flint of Scotland Yard to investigate.
The two cases collide at Marchbanks, the Drury family seat of over four hundred years, where a series of unnerving events interrupt the peace and quiet of the snowy countryside. A body is discovered in the middle of a frozen pond without any means of getting there and a rifle is fired through a closed window, killing a man but not breaking the glass. Only Spector and his mastery of the art of misdirection can uncover the logical explanations for these impossible crimes.