Kit Harington’s secret mission to protect Game of Thrones‘  biggest spoiler was far more elaborate than fans realize. 

You already know Team Thrones worked together with HBO to publicly obscure that Jon Snow was to be resurrected at the start of season 6. But long before the world saw Snow get stabbed by the Night’s Watch, Harington had to pretend he was leaving the show behind the scenes while making season 5 – because the rest of the cast wasn’t in on the secret.

Showrunners David Benioff and Dan Weiss told Harington he was going to eventually be revived just two weeks after the cast received the season 5 scripts in the summer of 2014. But the producers swore him to absolute secrecy. So for nearly a year, Harington had to convince his fellow Thrones actors and the show’s crew that he was leaving the show

“At first I thought I would find it fun,” Harington tells us. “This will be a fun game. But I had to lie to a lot of close friends and cast members and crew. The longer it went, the more I felt like I was betraying them. So I did end up letting people in, slowly.”

Some castmembers didn’t believe Harington was departing at all. Ser Davos actor Liam Cunningham, for example, “told me to f— off from the start,” Harington says.

While others bought the deception, at least initially – such as Sansa Stark actress Sophie Turner.

“Sophie Turner, bless her, wrote me a really long letter about how much she loved working with me – and I still got it,” Harington says. “That made me chuckle.”

By the time the scripts for season 6 went out last summer, the cast had pretty much figured it out.