The Juliet Code — Pepper Basham

Newlyweds Lord and Lady Astley Finally Reach Their Honeymoon Destination Only to Encounter a New Mystery in Need of Solving
 
Frederick and Grace Percy finally make it to Italy to enjoy a delayed honeymoon and explore the beauties of the historic city of Venice. To their surprise, their friend, Detective Jack Miracle, is also in the city, investigating a series of art heists starting at the house of eccentric millionaire, Laraby Covington. Drawn into a world of boat races, mysterious houses, and parties of the rich and unusual in Venice, Frederick and Grace learn of the existence of the Juliet paintings, (Renaissance paintings feature Shakespeare's tragic heroine) rumored to hold a secret code to an underground vault of similarly treasured artwork assumed lost over the centuries. As Freddie and Grace are pulled deeper into the mystery and their beloved Detective Jack disappears, can they use their wits and work as a team to find the thieves and Jack before it's too late. 
 
The Juliet Code is a Freddie and Grace Mystery, sequel to The Mistletoe Countess and The Cairo Curse.