For the quest missing in action http://elderscrolls.wikia.com/wiki/Missing_in_Action

how do i get the thalmor to release him without having to kill them all?

help me please >_< i want to know if i can get him released without causing mass murder ( i am doing an RP so i am doing my players actions as how i would do it in real life aka run the f away from a dragon )

You could try looking for a back door. I only remember one Thalmor in that area.