Looking For A Book
Hopefully this is allowed, and I'm at the end of my rope.

So there's this book, and I can't for the life of me (or my santity for that matter) remember the title or author. It was a young adult book (I think) and I have the feeling it was probably british, just based on some of the humor I remember.

In the beginning there's a man (he's of some political or social importance) upsatairs in his home, dressing for some type of formal event. it may have been his wife's funeral but don't hold me to that, it was black tie though, that's for sure.

There's a library in his town and (this is why I think it's british) the librarian is an orangutan, but it doesn't know. Something like, "If you were to point and say, 'Oh look, an orangutan,' the orangutan would turn around and ask where."

So the man gets sucked up(?) through the glass dome roof of the library and ends up back in time. Not too far back though. Here there is a plot to kill the king(?) and there's a band of assassins who are either hired or it's their idea. Something like this is descibed about the best assassin "didn't wear black becasue shadows aren't black," he wore grey becasue then he blended in perfectly.

In the showdown scene there are (I think) blow darts or poisoned wine involved.

There is also a cigarette case (or watch) which ends up in a pawn shop run by a monk... or else the monk just lives behind or near the shop... but he carried a broom to sweep the ants off the sidewalk in front of him so he doesn't accidentally kill one.

Honestly I should just re-write the book, I remember so much about it.

Thank you so much in advance!

cross-posted to a few different communitues

EDIT: Found it! Night Watch by Terry Pratchett. Thank you!