Book 17 in TheDresden Files series by Jim Butcher will be titled Battle Ground and is expected out this year, with a release date announced for a little more than two months after the release of Book 16, Peace Talks.

In December, a July 14 release date was announced for Peace Talks, and now we know its follow-up will be released right on its heels, on September 29. The latest in the bestselling series of contemporary fantasy novels was announced in the just released book trailer for Peace Talks, which premiered on io9 on Tuesday.

According to the trailer’s writer and director, Priscilla Spencer, who answered questions alongside Butcher in a streaming Q&A, the Peace Talks book trailer also includes scenes from Battle Ground, giving readers a sneak peek at both Book 16 and Book 17 of the series.

In Peace Talks, the first new book in The Dresden Files series since 2014’s Skin Game, private detective and professional wizard Harry Dresden is enlisted by the White Councilan international organization of wizardsto provide security for a summit between the supernatural nations of the world. But his job won’t be easy, because, according to the press release announcing the July release date for Peace Talks, “dark political manipulations threaten the very existence of Chicago.”

In the livestream Q&A, Butcher called Peace Talks “Harry’s worst weekend of the year.”

In Battle Ground, Chicago is once again under threat. Here’s the official synopsis for Book 17 in The Dresden Files series:

“Harry has faced terrible odds before. He has a long history of fighting enemies above his weight class. The Red Court of vampires. The fallen angels of the Order of the Blackened Denarius. The Outsiders.

But this time it’s different. A being more powerful and dangerous on an order of magnitude beyond what the world has seen in a millennium is coming. And she’s bringing an army. The Last Titan has declared war on the city of Chicago, and has come to subjugate humanity, obliterating any who stand in her way.

Harry’s mission is simple but impossible: Save the city by killing a Titan. And the attempt will change Harry’s life, Chicago, and the mortal world forever.”

Peace Talks and Battle Grounds are more intimately connected than typical entries in The Dresden Files, since the two were once a single novel that sprawled into what Butcher described as a “Frankensteinian thing.”

Eventually, Butcher agreed to split the manuscript into two books, with the condition that both books hit shelves in the same year.

The Dresden Files began in April 2000 with the release of Storm Front. In the 14 books released since, Butcher has developed an expansive world of magical factions, with wizards, werewolves, vampires and demons vying for control of the world. The five most recent books in the series have all debuted as #1 New York Times bestsellers.

Butcher expects to finish The Dresden Files series in 25 books, including a finale trilogy of novels.