Ex-spy 'Belle Boyd' is retired - more or less. Retired from spying on the Confederacy anyway. Her short-lived marriage to a Union navy boy cast suspicion on those Southern loyalties, so her mid-forties found her unemployed, widowed and disgraced. Until her life-changing job offer from the staunchly Union Pinkerton Detective Agency.

When she's required to assist Abraham Lincoln himself, she has to put any old loyalties firmly aside - for a man she spied against twenty years ago. Lincoln's friend Gideon Bardsley, colleague and ex-slave, is targeted for assassination after the young inventor made a breakthrough. Fiddlehead, Bardsley's calculating engine, has proved the world is facing an extraordinary threat. Meaning it's not the time for civil war.

Now Bardsley and Fiddlehead are in great danger as forces conspire to keep this potentially unifying secret, the war moving and the money flowing. With spies from both camps gunning for her, can even the notorious Belle Boyd hold the war-hawks at bay?

Cherie Priest has been hailed as 'the High Priestess of Steampunk' - and you can see why in this latest wonderfully written adventure.