Saturnine

"They don't want her. They want me."
Thomas Huxley is an agent in the twenty-sixth century. When his agency is breached and his identity revealed, his wife Zoe is kidnapped.
His friend Ariel, a time traveler, discovers that the kidnappers are working with an old enemy of hers, Bailey Tyler. The kidnappers demand a priceless painting in exchange for Zoe's return.
To find Zoe, Thomas enlists the help of other agents, a young queen, and a military commander. When the rescue plan is stalled, Thomas has to find his wife himself--but he and Ariel may not make it out alive.

Saturnine is a sequel to Flyday, but can be read independently.