I need classics thriller recommendations

Hi, this is my first post. Sorry if I'm breaking any rules, although I read them twice just in case.

Anyway, I recently finished reading The Count of Monte Cristo and The Da Vinci Code (in that order) and I loved them. I was looking for another classic thriller with a somewhat fast pace like these two.

I want to focus on thrillers because I think it's one of the genres I've read the least, especially classics. But if you have any other recommendations that seem appropriate based on these two books, they'd be more than welcome!

Again, please excuse any mistakes in my post.
Oh, and thanks for taking the time to read this!