Jeff Southard 
Year of the Dolphin [EPUB ebook] 

Set in the fabled city of Constantinople in 1014, Year of the Dolphin introduces two most unlikely crime fighters. Justin is a midlevel bureaucrat in the treasury department, while his wife, Sophie, is the chief lady-in-waiting for Princess Zoe, daughter of one of the two reigning emperors. Investigating a murder and jewel theft in the palace, they are drawn into a mystery that is truly Byzantine in scope. The trail of the shadowy forces behind the events in the capital city, which broadens to include high-ranking court officials, eventually leads them to Jerusalem and even to Cairo, where they find themselves and the princess in mortal danger.