Fiddlehead by Cherie Priest

Priest’s final Clockwork Century novel (after The Inexplicables) wraps things up nicely, once again turning a mash-up of too-worn genre tropes (steampunk, alternate Civil War, zombies) into a work of entertainment laced with social criticism. In 1879, as the Civil War continues to rage, scientist and ex-slave Gideon Bardsley’s invention, a massive computer called the Fiddlehead, has predicted that the zombie outbreak from the Northwest will overwhelm both sides if they don’t end the war. Working with ex-president Lincoln (long disabled from an assassination attempt), he enlists the Pinkertons, including their agent Belle Boyd, in an attempt to find allies in the South. Meanwhile, amoral businesswoman Katharine Haymes attempts to prolong the war for her own reasons. Priest again throws in a huge cast of characters, and the historical figures (Boyd, Lincoln, Grant) are as interesting as the fictional ones. New readers would benefit from starting at the beginning of the series, but returning fans will be satisfied by the elegant conclusion and will regret that a great series has ended. –Publishers Weekly