The Nasgareth may look like elves, but instead were created by an entirely different divine being, which admired the elvish looks and traits, but wanted to create his own army instead. One without Love.
A great treasure has been stolen from the Palace and taken to the nearby Temple to the Bitch-Goddess Atrath Klee. The King demands that the party go and retrieve it - the only snag is that the Temple is guarded by potent magic that will kill any male who steps inside. It's just as well that the King has a stash of Girdles of Gender Alteration for just this circumstance.