Fullmetal Alchemist Volume 14 by Hiromu Arakawa
The Elric brothers are in custody of the bad guys. Prince Lin from Xing is with them and volunteers to become a homunculus so he can be immortal. Too bad he's taken over by Greed, who doesn't want to give up the body and certainly doesn't want to go back to Xing and rule. The Elrics have a hard choice when they face King Bradley (seemingly the head of the bad guys), who wants to keep them as a valuable resource. If they agree to the king's demands, they will have to stop fighting the homunculi. Can they do nothing about the homunculi conspiracy and still find a way to get Al's body and Ed's arm and leg back?
The story is still exciting and deals with more complicated issues than you'd expect. The debate over the morality of using the philosopher's stone (which is created by mass murdering people and putting their souls into the stone) is interesting and creates more tension. I'm happy it's got more going on than the typical action and jokes in other manga.