Ben's childhood crush, Kai Green, asks Ben and Rook for help when her grandfather is kidnapped by the Forever Knights who are after a mysterious sword all the way in London hidden in a secret room under the river. Could what the knights seek be King Arthur's mythical blade, Excalibur?

As Ben, Rook, Rad, and Hobble fly through the Anur System to deliver something before they end up crashing into Anur Transyl, needing a device to power-up their engine. But as they walk through the planet, due to Anur Transyl being all but closed to the rest of the universe, the Halloweenish residents see Ben and his group as the monsters. But besides the angry mob and his friends being abducted by a Thep Khufan named Kupuhulu, Ben learns that Zs'Skayr (Ghostfreak's real name) has orchestrated the delivery to bring himself and the mentally restored Dr. Viktor back to their home system with revenge as an added bonus. Though his team got the upper hand, Ben ends up breaking the replacement device with them now stranded on Anur Transyl.