Apple TV's spy thriller has built its reputation on unpredictable twists and character deaths, and in Season 1, Sidonie Baker was shot during a mission and left comatose. Though she was later declared dead by MI5 leadership, viewers never witnessed her death or saw evidence of it, and all records of her were erased from agency databases, fuelling years of fan speculation that she survived.

The newly released Season 6 trailer has now confirmed that Sid is alive and will return to confront protagonist River Cartwright. This revelation pays off a long-standing mystery for viewers, though readers of the original Mick Herron novels had anticipated her eventual return.