As the train sped through Flat Top Tunnel, Elsa slid down a pile of chunks of coal, turning around and landing on her back at the bottom. She coughed a few times as she turned over and got back on her feet, quickly realizing that she was in the coal car, which led directly into the locomotive. As she brushed some coal dust off her nightgown and looked around the locomotive's interior, she saw Honeymarren sitting in the driver's seat.

"You?!"

Honeymarren turned around in surprise.

"Hey, Elsa. Miss me?"

"I thought you got thrown off and... you're driving the train?!"

"They put me in charge! The engineer had to check the light."

Out on the front of the locomotive, the two-man team responsible for driving the train, Smokey and Steamer, were examining the train's front light bulb.

"Here's the light!"

"I got it!"

"Careful! All right, now!"

"I got it!"

As Steamer extended his arm as far as it could go, he accidentally knocked it out of Smokey's grip. After two failed attempts to catch it, it flew out away from them, but Steamer grabbed Smokey's long beard, jumped forward and grabbed it out of the air. Smokey yelled out in pain as Steamer used his beard as a climbing rope to walk sideways up the front of the train to put the light back in.

"Well, how do you know how? All these levers and pipes and stuff, isn't it hard?" Asked Elsa.

Honeymarren laughed. "It's easy! Come here, I'll show you." Elsa stepped closer as she pointed to various levers and glass coverings with arrows beneath them.

"This big lever here, that's the throttle. And then this little one here, that's the brake. And those are the pressure gauges. And that rope is the whistle."

Elsa looked at a small tan-colored rope with a hand-grip on the end of it hanging from the roof.

"The whistle?"

"Mm-hm. You wanna try it?"

Elsa grabbed the rope and pulled it down, blowing the train's whistle.

"I've wanted to do that my whole life!" Said Elsa as she pulled the rope again.

Smokey continued yelling out as Steamer got closer to the light box.

"Hold still! Hold still! Don't move!" He said as he slammed the light back into place. It lit up as he closed the glass covering over it.

"Look!" Yelled Smokey. Steamer looked down and saw a light in the distance that the train was headed straight for.

"Light!"

Steamer finally let go of Smokey's beard, only for him to go up too fast and get his head stuck in the bell as he hit the ground. He quickly got back up and looked closer. The light was still there.

"Stop the train! Stop the train! Stop the train! Stop! The! Train!" Steamer yelled.

"What?" Said Elsa.

"He wants us to stop the train!" Said Honeymarren.

Elsa and Honeymarren eyed the levers.

"Which one of these is the brake?"

"He told me this was the brake." Said Honeymarren as she pointed to the small yellow lever.

"Who?"

"The engineer."

"The engineer?"

"Yes!"

"What about this red one that looks like a brake?!"

"No, no, he said this was the brake!"

"Are you sure? ARE YOU SURE?!" Demanded Elsa.

Doubting that she could convince Elsa, Honeymarren sighed as she sat back in the seat and covered her eyes, bracing herself for potential disaster as Elsa grabbed the red floor-mounted lever next to the small yellow one.

"Pull the brake! Stop the train!" Yelled Steamer at the top of his lungs.

Honeymarren uncovered one of her eyes, right as Elsa was about to pull the red lever. In a last second change of mind, Elsa released it from her grip and pulled the yellow one instead. The train's wheels stopped moving, generating orange sparks across the tracks as it steadily slowed to a stop. Steamer grabbed onto Smokey's beard to keep himself from falling off, and ended up pulling him out of the bell. Once the train stopped, Steamer came face-to-face with the source of the light.

"Caribou?"

The caribou snorted in his face. He looked around and saw a massive herd around the tracks.

"There can be no Christmas without the Polar Express arriving on time! Am I the only one who understands that?!" Yelled The Conductor as he trudged through the pile of coal and entered the locomotive. "You!" He said as he saw Elsa getting back up on her feet. "I should have known. Young lady, are you bound and determined that this train never reaches the North Pole?!"

"But look!" Said Honeymarren as she pointed to the herd, which was visible from out the window. The Conductor walked over and saw it.

"Caribou crossing?!"

"I make that herd to be at least a hundred thousand, maybe even a million! It's gonna be HOURS before they clear this track!" Said Steamer.

"A tough nut to crack!" Said Smokey.

"We are in some serious jelly." Said The Conductor as he, Elsa and Honeymarren walked across the side of the train to the front of it.

"And a jam."

"Tight spot."

"Up the creek."

"Up a tree!"

"Lost in the grass."

"I'll tell you what's grass! Our-"

Before he could finish, Elsa slipped on a small patch of ice and grabbed his beard to keep her balance. He yelled out again, and one of the caribous responded.

"Sorry." Said Elsa.

The Conductor, wanting to test something, yanked on his beard twice. He yelled out again, and this time the caribou started backing up. He yanked on his beard again, and after letting out his longest, loudest yell yet, the caribou responded again before they all started stepping off the tracks, clearing a path.

"Problem solved. All ahead slow!" Said The Conductor.

Smokey and Steamer got back into the back of the locomotive. Steamer blew the whistle a few times to clear any remaining caribou as Smokey started shoveling coal into the coal chamber that opened and closed via a button on the floor. Steamer retracted the brakes and gently pushed the throttle forward. The train started moving across the now Caribou-free tracks, steadily accelerating as it entered a mountain pass.