The Sinkhole — Brad V. Cowan

With the arrival of a mysterious letter from Cales estranged father, what looked to be a dull, hot summer becomes an exciting adventure for the Seven Stair Crew!

A series of clues sends the boys on a quest to find "The Empire" -- four super-secret skateboard sites with some of the most thrilling, gnarly set-ups around. Even Toby, the clumsy SSC wannabe, gets pulled into the action, despite the objections of some of the Crew.

But for Cale, it turns out that the quest for the Empire isn't just about skateboarding. It's also a personal journey of discovery -- about his own character and about the dad he never knew.