Yeah, you have to obtain a certain treasure, I forget the name of it offhand, it's some "valuable" like Wonky Talisman or some shit - then let them steal that (they will right away). Then you find their 'queen' - who is at the bottom of the temple after the interim save point, defeat her and you get all your items back.
Edit: It's also the same method used in the ice canyon if you're familiar with that shit. If you think the ruins are bad.. wait for temple of enlightenment
