We know quite a bit about Rogue One: A Star Wars Story (and we’re learning more every day), but there’s one thing that remains a bit mysterious: Galen, the character played by Mads Mikkelsen. We got our first — and only — glimpse of Galen during Star Wars Celebration Europe, but he’s yet to appear in any of the trailers for the upcoming anthology film and all we’ve had to go on until now is a rumor about how he figures into the story. In news that’s hardly shocking, there’s quite a bit of truth to that rumor after all.

Lucasfilm recently revealed a bunch of new Rogue One merchandise, including Catalyst, a prequel book written by James Luceno. The official synopsis for the novel sheds a little light on Galen’s background, and confirms that he is indeed the father of Jyn Erso, played by Felicity Jones:

War is tearing the galaxy apart. For years the Republic and the Separatists have battled across the stars, each building more and more deadly technology in an attempt to win the war. As a member of Chancellor Palpatine’s top secret Death Star project, Orson Krennic is determined to develop a superweapon before their enemies can. And an old friend of Krennic’s, the brilliant scientist Galen Erso, could be the key.

Galen’s energy-focused research has captured the attention of both Krennic and his foes, making the scientist a crucial pawn in the galactic conflict. But after Krennic rescues Galen, his wife, Lyra, and their young daughter, Jyn, from Separatist kidnappers, the Erso family is deeply in Krennic’s debt. Krennic then offers Galen an extraordinary opportunity: to continue his scientific studies with every resource put utterly at his disposal. While Galen and Lyra believe that his energy research will be used purely in altruistic ways, Krennic has other plans that will finally make the Death Star a reality. Trapped in their benefactor’s tightening grasp, the Ersos must untangle Krennic’s web of deception to save themselves and the galaxy itself.

Sounds like a real uplifting story, huh? It may be kind of a bummer, but it is definitely a compelling and relevant concept: A piece of advanced technology that could help make the world a better place turns into a weapon of mass destruction in the wrong hands.

What makes Rogue One particularly interesting is the idea that, thanks to the original Star Wars trilogy, we already know how things turn out. The Empire succeeds in building the Death Star (more than once, even), which means Jyn’s mission to retrieve the plans will ultimately fail, making the story something of an inevitable tragedy.

The film also stars Diego Luna as Captain Cassian Andor, Riz Ahmed as Rebel pilot Bodhi Rook, Forest Whitaker as Saw Gerrera, Donnie Yen as the blind warrior Chirrut Imwe and Alan Tudyk as K-2SO, with James Earl Jones and Jimmy Smits reprising their classic Star Wars roles as Darth Vader and Bail Organa, respectively.

Rogue One hits theaters on December 16.