prisoner_of_war_capture_effect

prisoner_of_war_capture_effect = {
	$TARGET$ = { save_temporary_scope_as = new_target }
	$IMPRISONER$ = { save_temporary_scope_as = imprisoner }
	
	if = {
		limit = {
			scope:new_target = {
				exists = liege
				OR = {
					is_playable_character = yes
					is_close_or_extended_family_of = liege
					is_spouse_of = liege
				}
			}
		}
		
		scope:imprisoner = {
			imprison = {
				target = scope:new_target
				type = house_arrest
			}
		}
	}		
	else = {
		scope:imprisoner = {
			imprison = {
				target = scope:new_target
				type = dungeon
			}
		}
	}

	imprison_hostage_tooltip_effect = { WHO = scope:new_target }
}

As written in game/common/scripted_effects/00_prison_effects.txt.