Meanwhile, lightning storms are breaking out all over town. They’re getting worse every week, and seem to enjoy striking kids who just want to pass science class and mind their own business. When Malcolm and Valentine discover a connection between the house and the storms, their situation goes from mysterious to crazy stupid dangerous. Someone is controlling the great machine, and their purpose is nearly complete.

In a race against time, the twins must uncover the chilling plan, the mastermind behind it, and the force that’s driving the deadly storms. They’ll hunt a powerful enemy that threatens their town’s existence, and the only clues are written in the sky.

Malcolm had never noticed the place before, but now he stood transfixed at his bedroom window. Despite the storm’s power, the house seemed strangely untouched—no damage, no fire, nothing.

The towering house sat across the street. Faded whitewash covered its three wooden stories, and tall brown grass curled around it’s worn wrought-iron fence. Malcolm guessed it had been abandoned for decades. Even the round window at the top revealed nothing but shadows.

Thunder boomed and his own window rattled. He rubbed his arms, feeling chilled. In the window’s reflection, he saw his twin sister move her queen.

“Check,” Valentine said.

“Two months of living here, and we didn’t notice it until now?” he said. “How can that be? It’s right across from us.”

Valentine’s eyes stayed on the chess board. “Noticed what, the storm?”

“No, that.” He tapped the glass. “Aren’t you listening?”

“I’m playing the game.” Valentine smirked. “Which is why you’re in check.”

Malcolm tore himself away from the window. He grimaced at his remaining pieces. “I thought we agreed to slow-play this one.”

“I had a good move.”

He blocked with his knight. “You always have a good move. Science geeks shouldn’t beat history geeks at chess. It’s not natural.”

Valentine grinned. “Well, maybe we should trade hobbies. I know some history.”

“Really. Which empire first settled the British Isles?”

She stared down at the board.

“Can’t answer, can you?”

“No, but I can do this.” She advanced her rook, removing his last bishop. “Check. Again.”

Malcolm winced and blocked with a pawn. His attention returned to the window. “How does it stand all that lightning?

Shouldn’t something that old just, like, catch fire and fall over?”

“Shouldn’t what fall over?”

“Geez, Val. Come on, get up and look at this.” Malcolm tugged on his sister’s arm until she followed him to the window. “Look right there. Wait for more lightning and you’ll see it better.”

“Mal, I don’t see—”

“Just keep looking, it’s . . . there!”

A massive bolt struck the corner of the old house, and a crack of thunder rumbled through Malcolm’s chest. For an instant, the sky lit up like mid-afternoon.

“Holy cow, that’s loud,” Valentine said. “The storms here are crazy!” Then she stopped, and Malcolm saw realization in her eyes. “Oh, wow. I hadn’t noticed that place before.”

“Right? That’s what I’ve been saying.”“But it’s just an old house. What’s the big deal?” She squinted, leaning closer to the window. “Though, I wonder who’d build a place with—”

Malcolm nodded fervently. “With no front door.”

“Actually, there aren’t any doors at all. Now that I think about it, I saw the back from the main road once. I just didn’t remember until now.” Valentine shook her head. “Weird.”

“Looks like each side has a window at the top. No doors, though.” Malcolm’s voice fell to a whisper. “No way in or out. Why would someone build that?”

Valentine stared for a moment longer, then turned away with a shrug. “Maybe Oma Grace knows.”

Malcolm’s shoulders fell. “You’re not even curious?”

“A little, maybe, but old stuff is your department. Show me something new and you’ll have my attention.” She glanced at her phone. “It’s getting late, and tomorrow is the first day of high school. I should go to bed. But first . . .” She moved to the chess board and slid a knight into position. “Checkmate.”

Malcolm came to her side and stared at the board, crestfallen. “Wait, wait, no way.”

Valentine patted his shoulder in mock sympathy and crossed the hall to her room.

“Hey wait!” he called. “I think I see a move—”

“Bedtime, Mal. G’night.”

Her bedroom door clicked shut. Malcolm studied the pieces a moment longer, sighed, and tipped over his king. Turning on the bedside lamp, he grabbed a book and settled onto the bed.

Hours drifted by as he let the historical adventure envelope him through the dead of night. Between chapters, he stretched stiff joints and watched the night sky battle on. His room had the best view of the storm, which appeared to be growing angrier by the hour. Lightning flashed constantly behind the dark clouds, and the air rumbled with rolling thunder. His brow furrowed as he noticed that frost had formed on the edges of his windows.

Frost seems odd for summer. Maybe we’re close to the storm center.

Malcolm picked out the largest bolts of lightning and the most intense thunderclaps. Mentally he counted the seconds between them, hoping to guess their distance away. Wait, that can’t be right. He counted again and got the same result.

The delay was identical every time—one and a half seconds between lightning and thunder. Strike-pause-boom, wait, repeat. After twenty minutes of counting, the cycle still ran like clockwork. Is that normal around here? Valentine probably knew but must be dreaming by now. Maybe he’d ask her tomorrow.

As Malcolm turned away from the window, something brushed the corner of his vision. A burst of light, but not like the others. He whipped back around and stared into the night. A bolt of lightning and crack of thunder greeted him again.

Whatever it was, it had looked different than the lightning—brighter, and a slightly different color. Light must be playing with my eyes. He rubbed them and moved to turn away again.

Probably just—no, there it is again!

He saw it this time—a strange pulse of blue-white light. It hadn’t come from the clouds. It had been closer to eye level and from the direction of—

Malcolm lunged at the shelf over his headboard. Grabbing an antique spyglass, he pointed the lens across the street, toward the house with no doors. He held deathly still, his eye trained on the front window.

PULSE!

A beam of light lanced from the window, piercing the inky darkness. One-point-five seconds later the sky erupted in thunder and lightning. Malcolm felt like he’d been dunked in ice.

“Pulse-lightning-boom. House-sky-air, every time. What on earth is—”

PULSE!

A man’s face glared at him through the window.

With cold fury, he stared into Malcolm’s room and straight down his spyglass. Malcolm froze under those accusing eyes as they pulled him toward the window. His panicked breath came ragged and hoarse, his muscles refused to budge.

PULSE!

The face disappeared.

Malcolm snapped back like a broken rubber band, yelping as he fell from his bed. He smacked onto the floor and collided with the dresser. Antiques and picture frames toppled onto him as he sprawled on the floor, groaning.

“Mal?”

A moment later Valentine staggered in, squinting. “What are you doing? It’s like two a.m.”

Malcolm sprang up and dragged his sister to the window, shoving the spyglass into her hands. “Look across the street.”

“At what?”

“You know what! Come on, just do it.”

Sighing, Valentine held the spyglass to her eye. “What am I looking for?”

“You’ll know. Shouldn’t be long now.”

Malcolm watched with her, determined to catch the next pulse. But after a moment, he knew something was wrong. It should have happened already. “These pulses of light were coming from the window across the street! I . . .” What’s taking so long? Minutes passed as they watched absolutely nothing happen.

Valentine handed him the spyglass. “Well, this was fun. Go to sleep. Tomorrow is a school day.” She glanced out the window as she turned to leave. “Hmm, looks like the storm broke. G’night.”

Deflated, Malcolm studied the sky as his twin closed the door. The lightning had stopped, the thunder had quieted, and the house had become a dark, old shell again. He dropped onto his bed with a sigh.

Maybe the light just played tricks on me.

But the face in the window would not leave his mind. Sleep eluded him, and he found himself shivering at the memory of those eyes. Despite his efforts to believe otherwise, Malcolm knew what he’d seen.

“Someone’s inside that house.”