Can I play my Assassin through the original RP campaign?

2 of my buddies have the original Guild Wars game, and have just started playing through the storyline. I'm wondering if I'll be able to roll an Assassin and play with them, in the Tyria missions? They're still in pre-searing.

Thanks in advance!

Yeah, you can play all the missions after Lion's arch if, of course, you own prophecies.