This is one of a series of comic stories about the Minerva Club, an association of warm-hearted criminals. The others are The Trojan Crate, Flint's Diamonds, The Ransom of Angelo, and A Stroke of Genius.
The three Head brothers disapprove of their sister's fiancé, but are cajoled into arranging her wedding. They steal a wedding dress, a lorry load of champagne and a wedding cake. At the reception, however, it turns out that the cake is not real but is a plaster-of-paris display cake. The groom assumes this is a deliberate insult and is so exasperated that he takes on the three brothers with his fists, and almost ensures the termination of their club memberships, until somebody notices something in the wreckage of the cake.
Ellery Queen's Mystery Magazine #242, January, 1964.
Included in the collection The Minerva Club and other stories. USA, Crippen and Landru, 2009.