I lifted myself from the ground with my ears ringing and my chest filled with smoke. I looked around the dark cabin. The people at the far end of the cabin were rushing towards the front. Waves of water crashed behind them as it took out the settling flames. The others in front had been knocked to the cabin floor, but everyone looked okay.

"Is the train still moving?" I said and steadied my feet on the shaky cabin floor.

"It's going, but it slowed down," Nate said and pressed a button of the control panel that kept the lever in place, "I think Gen hit us from outside the Union bounds, but I don't know how without the network."

Nate paced around the cabin when Eve pointed to a round fist-sized disc on the window of the train.

"Guys, what is that?" Evee said as she back away from the window.

The black disc was stuck to the window. It's spider-like legs held onto the glass, and a red dot blinked at its center.

"No," Nate said and jumped towards the window, "She couldn't have. Not without a -"

"Nate, what is that?" I said and stared into the blinking red light.

"I've only seen them once before," Nate said, "My parents warned me about them. It's a magnetic explosive."

I inched away from the window, feeling the tight walls of the cabin and the vast body of water beneath as it strangled me at the thought.

"Magnetic?" Macie said from her slumped seat in the corner of the cabin.

"It's an explosive tied to an object like a magnet," Nate explained, "Wherever the object goes, the magnet follows."

"So that means there's something on this train that the explosives are following?" Mat's mother said.

"Right, so Gen wouldn't need the network to aim at us," Nate said and pointed to the black disc, "We need to figure out where the other magnet is."

"What about those steel bracelets," Evee father said, "I've never trusted those things."

"It can't be our bracelets," Mat said and looked down at his bare wrist, "Gen took those when she locked us away."

"But I thought I saw some guards passed out back there," Evee said and pointed to the back of the cabin, "Could it be one of their bracelets."

"No way," Nate said and twisted his mouth, "Not the way I shocked them. The bracelets are useless after that. Something else is tied to the magnets."

"Everybody," Valencia said as the train was rocked again by an explosive in a back cabin, "Look around, and try to find anything that looks suspicious."

"Nate," Mat said and stood over the controls to look closer at the black disc, "If we can't find the other magnet, I think I know a way to disable this one."

"Do what you can," Nate said as he pushed away a pile of books.

Mat nodded and reached into his pocket to pull out a small metal block.

"It that a -?" I said as a memory rushed into my soaring heart.

"Just like the ones we use to use in camp," Mat said and smiled with soft eyes, "As soon as I saw it behind that class in the tower, I knew Alger was looking out for me."

Mat rolled up the sleeves of his long shirt and hovered the metal block over the black disc from behind the window with precision. He let the block get close then pulled it away like it was on fire. As the red light of the disc began to fade, Mat pushed his hair out of his eyes to look at it closer.

"If I can just get the wires inside hot enough to melt," Mat said and exhaled loudly, "I might be able to disable this one."

"We'll still need to find what sent this one," Nat said as he moved a shelf away from the wall, "There could be others coming to replace it."

"Let's just hope this old thing still has some juice in it," Mat said and hovered the metal block over the disc again.