We have different games geared to different groups. All of our games would work for 30 if you purchase an extra character packet. For ages 13-17, I would suggest the following games:
Murder at the Four Deuces Tame:
http://www.dinnerandamurder.com/games/4deucesteen.htmThe Immortal Murders:
http://www.dinnerandamurder.com/games/immortals.htmYou could also use A Killer Reunion or Class of '57, but these are written for church groups and so squeaky clean that I personally think they suffer for it. Ultra conservative groups really enjoy these 2 though, so if your group is looking for something along those lines, these would work.
Hope this helps!