«Black Chamber» by S.M. Stirling

The first novel in a brand-new alternate history series where Teddy Roosevelt is president for a second time right before WWI breaks out, and on his side is the Black Chamber, a secret spy network watching America's back. In 1912, just months before the election, President Taft dies suddenly, and Teddy Roosevelt wastes no time in grabbing power as he wins another term as president. By force of will, he ushers the United States into a new, progressive era with the help of the Black Chamber the mysterious spy organization, watching his back. Luz O'Malley-a brilliant, deadly, and young Cuban Irish American agent of the Black Chamber-heads to Germany. She's on a luxury airship swarming with agents of every power on earth, as well as conspirators from the Mexican Revolutionary Party and the sinister underground of the reborn Ku Klux Klan, yet none know her true identity. Her anonymity will be essential as she strives to gain the secrets of Project Loki, an alarming German plan that Roosevelt fears will drag the U.S. into a world war. To gather this intelligence, Luz will have to deceive the handsome yet ruthless Baron Horst von Duckler. She, along with naive Irish-American Ciara Whelan, has to get this vital information back to the U.S.-or millions of lives will be lost.