The Rookie (TV trailer with added Nathan Fillion).

So, what happened to Nathan Fillion’s character in Castle after the series wrap-up?

Well, maybe, after a life-altering incident, he becomes an LAPD officer.

As the force’s oldest rookie, he’s met with scepticism from some higher-ups who see him as just a walking midlife crisis. If he can’t keep up with the young cops and the criminals, he’ll be risking lives including his own.

But if he can use his life experience, determination and sense of humour to give him an edge, he may just become a success in this new chapter of his life.