Then, without warning, the big sheepdog sprang forward. With another shrill yip, Dogface raised his enormous front paws—and leaped on to Kermit.

Kermit let out a startled cry and stumbled back against the wall. Bottles and jars shook on the shelves behind him.

Dogface began barking wildly, uttering shrill, excited yips. The dog jumped again, as if trying to leap into Kermit’s arms.

“Down, boy! Down!” Kermit squealed.

The dog jumped again.

The shelves shook. Kermit sank to the floor.

“Down, boy! Down!” Kermit shrieked, covering his head with both arms. “Stop it, Dogface! Stop jumping!”

The excited dog used his head to push Kermit’s arm away. Then he began licking Kermit’s face frantically. Then he began nipping at his T-shirt.

“Stop! Yuck! Stop!” Kermit struggled to get away. But the big dog had Kermit pinned to the floor.

“What’s going on?” Andy cried. “What’s gotten into that dog?”

“Kermit’s mixture!” Evan replied. He dove at the dog, grabbed Dogface with both hands, and tried to tug him off Kermit.

Dogface spun around. With another high-pitched yip, he bounded away, running at full speed across the basement.

“Stop him!” Kermit cried. “He’s out of control! He’ll break something!”

CRAAAASH.

A shelf of canning jars toppled to the floor.

Barking loudly, the dog bounded away from the shelf and began running in wide circles, his big paws clomping on the tile floor. Round and round, as if chasing his tail.

“Dogface—whoa!’ Evan called, chasing after the sheepdog. He turned back to Andy. “Help me! We’ve got to stop him! He’s acting crazy!”

Dogface disappeared into the laundry room. “Dogface—come back here!” Evan called.

He burst into the laundry room in time to see the dog crash into the ironing board. It toppled over, along with a stack of clothes that had been resting on it. The iron clattered over the hard floor.

Dogface yelped and climbed out from under the spilled clothes. Spotting Evan, the dog’s stubby tail began wagging—and he leaped across the room.

“No!” Evan screeched as the huge dog knocked him over backwards to the ground. Dogface frantically licked Evan’s face.

Behind him, Evan heard Andy laugh. “Too much energy! He’s acting like a crazy puppy!” she declared.

“He’s too big to think he’s a puppy!” Evan wailed.

Dogface was sniffing furiously under the washing machine. He pounced on a large black ant. Then he turned and came bounding over to Andy and Evan.

“Look out!” Evan cried.

But the big sheepdog lumbered past them, back into the other room. They followed him, watching him roll over a few times, kicking his big, furry paws in the air.

Then Dogface jumped to his feet—and came charging at Kermit.

“Whoa! Whoa, boy!” Kermit cried. He turned to Andy. “You’re right. This is just the way Dogface acted when he was a puppy. The mixture gave him too much energy!”

The sheepdog crashed into an old couch against the wall. He climbed up onto the couch, sniffing the cushions, exploring. His stubby tail wagged furiously.

“Dogface, you’re not a puppy!” Evan cried. “Please listen to me! You’re too big to be a puppy! Dogface—please!”

“Look out!” Andy shrieked.

The dog jumped off the couch and went running full speed toward Kermit.

“No! Stop!” Kermit cried. He dove behind the lab table.

The dog tried to slow down. But his big legs were carrying him too fast.

Dogface crashed into the lab table. Bottles and beakers flew into the air, then crashed to the floor. The table toppled over on top of Kermit.

The shelves fell off the wall, and all of the jars and tubes and beakers tumbled to the floor, shattering, clattering, chemicals pouring out over the floor.

“What a mess!” Evan cried. “What a horrible mess!”

He turned—and let out a loud gasp.

Aunt Dee stood in the doorway. Her mouth was opened wide in surprise, and her eyes nearly bulged out of her head.

“What on Earth is going on down here?” she shrieked.

“Uh … well …” Evan started.

How could he begin to explain? And if he did find a way to explain, would Aunt Dee believe him?

Aunt Dee pressed her hands against her waist and tapped one foot on the floor. “What has happened here?” she demanded angrily.

“Uh … well …” Evan repeated.

Kermit spoke up first. He pointed an accusing finger at Evan. “Evan was teasing the dog!” he cried.

Kermit’s mom glared angrily at Evan. “I’m paying you to take care of Kermit,” she said sternly. “Not to play silly jokes on the dog and wreck my house.”

“But—but—but—” Evan sputtered.

“Evan didn’t do it!” Andy protested.

But her words were drowned out by Kermit, who let out a loud, phony wail—and burst into tears. “I tried to stop Evan!” Kermit sobbed. “I didn’t want him to tease Dogface! But he wouldn’t stop!”