The vorpal sword is the one thing that can kill an ogre, but Mallory will have to trust Jared to acquire it. They risk it all by following a hag to the Goblin Market. Thimbletack's left to defend Spiderwick.

Mulgarath's plans are coming to fruition as townsfolk either succumb to the sleeping sickness or become the ogre's servants. The gang launches a daring prison raid to rescue Jared. The Grace family must reunite to defeat Mulgarath.