A powerful Belgian financier vanishes from his private aeroplane between England and Brussels, leaving behind only offended respectability, conflicting witness statements, and a rear door found suggestively unlatched, and the Belgian Detective is summoned into a “locked-room-in-the-sky” puzzle where perfume, cigars, copied numbers, and an ominous note—“HAREN. TWELVE MINUTES.”—point to a disappearance that may be theatre, not physics; as the investigation shifts from headlines to ground routines, a hidden service hatch, a hurried taxi, and a blackmail list marked PAYÉ reveal a brutal truth about leverage, misdirection, and the kind of men who believe money can purchase invisibility; inspired by historical crime of its era while remaining entirely fictional, The Vanishing of Monsieur d’Aubel is an original Golden Age–style mystery of wealth, access, and the dangerous minutes when everyone thinks nothing important can happen.