Ziggy, Rashawn, Jerome, and Rico -- the Black Dinosaurs -- are thrilled

to discover that their hometown was a stop on the Underground

Railroad. Even more exciting, their new friend Mr. Greene has

given them an old map that shows a secret passage, dating back to

the days of the Railroad, right under their own school! How can

the Black Dinosaurs resist making plans to check it out?

When a trapdoor slams behind them, locking them in the tunnel,

there's only one thing they can do -- plunge deeper and deeper into

the darkness. Where will the tunnel lead them? And will the old,

crumbling walls hold until they find their way to the end?