Hostage Rescue

[Shifty]

I would like to make a new objective map where the objective is to rescue someone, but the person that needs rescuing would be an actual player not ai, so basicly untill a team mate gets to him hes stuck in jail. i could do a jail door with triggers, but how would i get it to randomly pick 1 person from say the allies to be jailed? This is just an idea and i dont know how it would play.