Henry Alfred Grummorson is the great-great-great-great-great-great-great-grandson of King Arthur, one of the bravest knights to ever live. On the day Henry turns six years old, he wakes up early, mounts his trusty donkey, Knuckles, and goes out in search of adventure.

Along the way, he encounters a Dragon, a Cyclops, and a Griffin, but none of them will have "ado" with Henry. Desperate for a real battle, Henry seeks out the most fearsome of all the beasts: the Leviathan. But has Henry met his match at last?