Crystals

When ten-year-old Spencer and his little brother, Justin, go under the couch for an adventure, they are shocked when they are dumped in deep water. They are in a large bay far from land, and Justin isn't a good swimmer. But that's only the start. They soon discover that the island they are trying to get to is full of giants!

And what is the huge moon-like circle in the sky? The boys explore strange structures around the land, including monoliths and enormous pyramids. Soon, time is running out and they need to return to the dangerous water to find their door home. The bay is so huge ... how are they going to find it?

Crystals is the tenth book of twelve in the series about Spencer and Justin's exciting and dangerous adventures in the mysterious under-the-couch world.