"Take the tunnel on the right," Optimus Prime orders. "Autobots, advance!"

Bumblebee leads the way. It is so dark, he turns on his headlights.

"It's spooky in here," says Buster. "And what is that buzzing noise?"

"Don't worry," says Bumblebee. "We'll be out soon."

But the tunnel keeps going. The buzzing grows louder. The tunnel twists and turns, deep into the mountain.

This must be the wrong passage, Optimus Prime thinks. "Autobots," he orders, "reverse course!"

But at that moment is a rumbling noise. A rock slide begins to rush down the tunnel. The Autobots cannot turn around.

"Hold on!" cries Bumblebee. Buster and Sparkplug hold on tight. Bumblebee and the other Autobots slide down ... down ... down.

With a deafening crash, they reach the bottom of a canyon. The path they had been following is no longer there. The entire corridor has caved in!

"Check for injuries!" cries Ratchet. One by one, the Autobots report.

"Minor dents," says Mirage.

Continue.