David, Milo and Futz are just putting the finishing touches on their scale model of the Battle of Waterloo when a samurai warrior comes staggering unexpectedly out of a broom closet and squashes the British army flat.

The samurai says he knows David's father, a famous archaeologist who mysteriously disappeared five years before on a top secret expedition.  He hands David a key he claims can unlock the hidden doors between worlds.  There's no time for further explanation, however, because a whole army of monsters are hot on his heels.

Using the key to escape, the boys suddenly find themselves in a world of delusional hotel managers, short-sighted Troglodytes, carnivorous trees, and a bloodthirsty pirate named Sharkface, who is known for his evil disposition and fearsome (albeit slightly impractical) dental work.  Sharkface believes the key can unlock a priceless treasure, and isn't about to let three 15-year-old amateur historians get in his way.

Desperate to solve the mystery of the key and his father's disappearance, David and his friends are caught up in a chase that will lead them right to the end of the world...and the legendary island that lies beyond.