[He'll snatch the key and keep running towards the library. Hopefully the other two are following him.]

The trapdoor, the door in the billards room, and the door here. There's three ways to get into the smoking room and three of us. We each take as many keys as we can and try a different entrance.

I don't know how long it'll take, but we don't have any other options I can see here. If we can get to him fast enough, we might just have a chance.