Arg, this one has been on my mind for so long!

I remember the main character being a special agent or something, and he's on a mission. He's had to travel to another country to complete his mission, and while there, he is staying at a hotel. When he is in the room, he is however surprised by a visitor. The visitor isn't actually any enemy, but someone who he must stay in the room with for his own protection, or something.

I also remember another part where they're in a battle scene, and flying over a rectangular lake surrounded in some buildings and trees.

Another scene is when they all head to a university library to look at history books to attempt to "figure the answer out".

Just another part, maybe, I remember a building exploding.

I'm really not sure! Hopefully someone can help..