The Assassin's Honor - Robert Macomber (Honor Series, Book 12)

In 1892, Commander Peter Wake has left the world of espionage behind and is back in the sea-going navy. But duty has called him from his new Spanish lover back to Key West to investigate an assassination and prevent another one all of which leads him to old German foes in Mexico as well as Spanish ones in Cuba and Tampa. The life of the great patriot of Cuba, Jose Marti, is at stake."