Why is "Doctor Who" the greatest TV show ever?
Steven Moffatt can tell you why: because of the lives it's touched and the people it's inspired.
"Who" writer and producer Moffat grew up a fan of the long-running time-traveling adventure before taking charge as showrunner in 2009, shepherding the series through its 50th anniversary.
It's the final episode for both Moffat and current Doctor Peter Capaldi, with new star Jodie Whitaker appearing in the closing moments.
Capaldi wasn't present at the screening at London's Science Museum, but he did send a message thanking his friends on the show and wishing Whitaker good luck.
I was in the audience with other press and fans, watching the episode and transcribing a question-and-answer session with Moffat and the cast.