“And that’s a loose end.”

Through the tiny vent slots, Spencer watched an Extension Grime and a Rubbish pace the hallway. It didn’t matter how well concealed he was in the locker, Spencer held perfectly still, not even daring to breathe.

“Where’d they go?” one of the Pluggers said. “I was right behind them.”

“They can’t be far,” said the other. “Let the monsters sniff them out.”

Spencer felt his legs begin to quiver. The last thing he needed was for his knees to knock against the metal locker. From his limited viewpoint, Spencer saw the Extension Grime leap across the hallway. There was a resonant clang as the monster’s sticky fingertips latched onto the bank of lockers.

Daisy’s heavy breathing suddenly changed to a faintly hummed tune—a Disney princess song, to be exact. The Extension Grime was too close. Its breath was distracting Daisy! Spencer reached for his can of air freshener, but the locker was too small, pinning his hands at his sides.

Then his view was blocked entirely as the Grime’s huge head slid across the locker. Spencer pinched his eyes closed, waiting for the massive Extension Toxite to rip open the lockers and eat him and Daisy in one gulp.

The locker door rattled. Spencer opened one eye and instantly wished that he hadn’t. The Grime’s snakelike tongue had slithered through the vent slot. Daisy was getting louder as her humming neared the chorus. The forked tip of the monster’s tongue brushed her cheek, and she giggled.

“Where have you morons been?” asked a new voice from the hallway. The Grime’s tongue withdrew, and the rider directed it away from the lockers.

Spencer, trying not to let his panting breath betray him, leaned his head forward and peeked through the vents to see an Extension Filth sauntering down the hallway. The man on its back looked annoyed to find his companions.

“We were searching for the Rebels,” answered the Rubbish Plugger.

“We already caught the Rebels,” said the Filth Plugger. “Leslie’s holding them in a classroom on the main floor. Wants everyone there.”

The Extension Grime cast a final hungry look toward the lockers, but the Plugger twisted the dial and steered the monster away. Daisy’s humming came to an abrupt stop, and the dim hallway was totally silent.

Spencer finally sighed, the muscles in his shoulders relaxing a bit. “Daisy?” he whispered, his lips less than an inch from her ear.

“Yeah?”

“I think you locked us in.”

“That’s okay,” she said. “We can Windex the door and break out.”

“Except,” Spencer strained again to reach the items on his belt, “my arms are pinned.”

“Here,” she said. “Maybe I can reach yours.”

Spencer’s heart was still hammering. Luck had saved them this time. Another moment and the Extension Grime would have alerted its master. If it hadn’t been for that Filth Plugger calling them back . . .

Leslie’s patience was no doubt wearing thin. Spencer didn’t know how long he could keep her interest on the paper-towel map before she decided to take Alan and leave.

Spencer needed to figure out what classroom the Rebels were being held in so he could lead a rescue. While Daisy managed to grab his bottle of Windex, Spencer squirmed his hand into his pocket. The bronze medallion was still there. If he could reach it, Spencer might be able to see through Walter and find out exactly where the others were.

The darkness of the locker dissolved into white light as Spencer’s fingers brushed the medal. As the light cleared, he got an instant fix on Walter’s location. He was on the main floor of Alsbury High School, room 18.

Looking through the warlock’s eyes, Spencer saw Leslie Sharmelle dismounting her armored Filth. Half a dozen Pluggers were perched around the room, making any kind of escape impossible.

Leslie approached the Rebels with a plunger in hand. The extension cord stretched between her and the beast, its orange color matching her prison jumpsuit. She reached to her belt and unclipped a walkie-talkie. Lifting the device to her lips, she pressed the button.

“We have them, Mr. Clean,” Leslie said.

“Mr. Clean.” Bernard scoffed. “Kind of a cheesy name for the arch villain—”

Before he could finish, Leslie brought the wooden handle of her plunger across his face. Bernard slumped forward, blood on his cheek.

The walkie-talkie made some noise, and Spencer recognized the voice of the third warlock. “Eliminate them all.”

Leslie pressed down the button to respond, but Alan shouted, his voice carrying through the device. “Hey! Leslie made me an agreement! You’ve got me now, so let my friends go free.”

Mr. Clean’s voice came through again. “Leslie isn’t in a position to make agreements. Besides, there’s been a complication.”

“What complication?” Alan asked as Leslie pressed down the button.

“Leslie was supposed to stop you before you solved that thirteenth clue. I don’t like loose ends,” he said. “Your kid has the map to the landfill. And that’s a loose end.”

Alan grunted in frustration. He beckoned for Leslie, and she held the button on the radio once more. “Why don’t you do this yourself?” Alan taunted. “Why send Leslie? Too comfortable in your office to come down and get your hands dirty? Why don’t you show your face, coward?”

The response was laughter, so loud that the speakers crackled. “Once you are out of the equation, everyone will know my face.”

There was a flash of white light, and Spencer stumbled out into the hallway. He almost collapsed to the floor, but Daisy threw her arms around him for support. While he had been swept up in the vision, Daisy had Windexed the locker and shattered the doors.

Spencer groaned in pain as his bare feet scuffed across the floor. Looking down, he saw a streak of blood on the tile and felt the sting of broken glass in his heel. In no time, Daisy had him seated on the floor. She squinted one eye shut as she pulled out the glass fragment. Her orange healing spray misted over his foot, and Spencer felt the wound seal instantly.

“I just checked on Walter,” Spencer said. “Mr. Clean doesn’t want us getting away with the map.” He held out the paper-towel roll. “Leslie’s going to kill the others.”

“Everybody?”

Then Spencer realized who had been missing from his warlock vision. “Not everybody.”

It took longer than Spencer wanted to find the secret bathroom. The hallways were clear, which meant that the Pluggers were still in room 18 with Leslie. But there was no way of knowing how long that would last.

Spencer and Daisy entered through the broken brick wall. The hidden bathroom was a mess! Leslie’s Extension Filth had destroyed several stalls, and there were deep claw marks in the tile. But one thing remained untouched. In the middle of the bathroom, an inch of cardboard tube jutted up from the floor.

Penny was still under there.

It wouldn’t be easy to free Penny from the hard floor. Spencer remembered his dad’s warning. If they weren’t careful, the Windex might accidentally turn Penny to glass.

They started with a gentle mist. The floor shimmered in iridescence before turning transparent. Penny was lying several inches under the surface, her eyes closed tightly and her body stuck in a tensed position.

Spencer used his razorblade to smash out the first layer of glass. Then, with the Windex nozzle set to a fine stream, he and Daisy targeted the floor around Penny’s body.

Spencer had broken out a few more pieces when, suddenly, Penny’s hand burst free. She twisted sideways, the transparent floor around her cracking like ice. At last, she sat up and spat out the cardboard breathing tube.

“I was beginning to think that you guys had left me,” Penny said, shaking bits of tile from her short red hair.

“We did,” said Daisy. “But then we came back.”

Penny blew a chunk of floor from her nose and rose on shaky legs. “What happened? Where’s everyone else?”

“Leslie’s here,” Daisy explained. “And she’s got a gang of Pluggers with her. Their Extension Toxites are covered in armor!”

“They captured Walter, Bernard, and my dad,” Spencer said. “I hope you’ve got a plan, because I’m fresh out.”

Penny checked her janitorial belt. “I’ve been lying under the floor for the past half hour, brainstorming worst-case scenarios.” She nodded. “I’ve got a plan. But Bernard’s not going to like it.”