The Helm of Zork is a legendary golden helmet which allows the wearer to impersonate any person of their will. It is of note that the illusion is particularly great, and the most wise of magic users cannot detect it.
It had been lost for many centuries, and many legends and theories existed about its final location: from far beyond the distant desert and a shipwreck in the deepest reaches of the ocean, to caverns deep underground.
In reality it was guarded in the turret of an ancient castle near the Flathead Mountains (according to the description, it is possible that it was the summer castle of the Flatheads in Fenshire). It was standing on a pedestal in the middle of a room; someone had locked the door from inside and then left. A large mirror was on the opposite wall.
The persons guarding the Helmet installed a high technology security measure against any thieves. Breaking the glass transom above the door, would trigger an ear-splitting alarm, steel doors slam shut around the landing, trapping the thieves, posion-tipped darts are shot and jets of poison gas puff from holes in the wall, chainsaws descend from the ceiling and panels open revealing laser-armed robots.
Jeearr's actions caused Syovar to be unavailable for the Conference of Quendor that would put an end to wars; his son, Logrumethar thought of the Helm of Zork that would allow him to impersonate his father and ensure a successful outcome for the treaty. Bivotar and Juranda were teleported near the castle where the Helm was resting, and looking for it, they reached its tower.
The kids teleported back to the Castle of Zork with the Helm; in Quendor, the magic of the Helm fooled everyone and the Treaty of Quendor was successfully signed.