The Grand Tour; or the Purloined Coronation Regalia — Patricia C. Wrede; Caroline Stevermer

On their honeymoons, Kate and Cecelia confront a plot against Europe

Ocean voyages do not agree with wizards, and seasickness during the Channel crossing is the price Cecelia must pay for her budding magical skill. As her nausea ebbs, she is comforted by her new husband, James, and the knowledge that at long last they are on their honeymoon. In their company is Cecelia's cousin Kate, newly minted as the Marchioness of Schofield, and her husband Thomas. The shared journey guarantees the two couples a happy start to married life, if they can survive the perils of the Continent.

In Calais, a mysterious woman visits Cecelia with a package intended for Thomas's mother. Inside is an alabaster flask of noble manufacture, one of the royal artifacts that have been vanishing all over Europe as part of a magical plot against the French crown. This is no simple honeymoon: On their tour of Europe, Kate and Cecelia must save the monarchy from an emperor-in-exile named Napoleon.