The Convival Codfish — Charlotte MacLeod

After years of toiling upward through the ranks, Jeremy Kelling has finally attained his goal: to preside as Exalted Chowderhead over the Annual Scrooge Day revels of the Comrades of the Convivial Codfish. Suddenly, at the height of the ceremonies, Jeremy discovers that he's been robbed of his extremely valuable emblem of office. The Great Chain of the Convivial Cod is gone! He calls his new nephew-in-law, Max Bittersohn, who isn't inclined to take the Codfish seriously -- until Jeremy falls victim to what may, or may not, be a particularly vicious practical joke. From then on, it's champagne, caviar, and cold-blooded mass mayhem in high society as Max puts his life on the line to find a killer.