Sam Heughan dropped by “The Tonight Show” on Thursday to promote the long-awaited sixth season of “Outlander”.

While telling host Jimmy Fallon what’s in store for the new season, Heughan also revealed he knows how the series will conclude.

“Diana Gabaldon, thank you Diana. She’s written this amazing series,” Heughan told Fallon, referencing the author of the book series on which “Outlander” is based. “She’s on book 10, we’re about to do book seven in season seven so we’ve still got a bit of a way to go.”

READ MORE: ‘Outlander’: The Official Season 6 Trailer Is Here

“Do you know how it ends?” asked Fallon.

“I do, I know how it ends. She revealed to me the ending a long time ago actually,” Heughan responded.

“So she’s written the ending but not written it. It’s in her head?” Fallon queried.

“Yeah, it’s in her head and my email chain,” Heughan clarified. “Let’s hope I don’t get hacked.”

READ MORE: Caitriona Balfe Explains Why She Had To Appear Virtually And Not In-Person At ‘Outlander’ Season 6 U.K. Premiere

“Outlander” returns Sunday, March 6 on W Network.