By the time Joe woke up, the food was gone, and Dumpling was asleep in the sock drawer, his nose stained pink from the jam.

Joe tiptoed around his room, getting ready for school. He was hoping he might actually be able to sneak off without Dumpling today, but as he picked up his bag to leave, the hamster opened one beady red eye and squeaked, “Is it time to go?”

Joe frowned. “I’m only taking you if you promise to be good.”

Dumpling nodded. “I promise! Are you sure your plan will work?”

“Of course!” said Joe confidently. But he wasn’t sure at all. He still hadn’t worked out what he was actually going to say when he got to Oliver’s house.

After a boring math class—which Dumpling spent swinging off the edge of Joe’s desk by two paws, chewing a pen cap—they went outside at recess to track down Oliver.

They found him on the far side of the playground; he was kicking a ball with Toby and two other friends.

“Hey, Oliver!” Joe called.

Oliver waved. “Hi, Joe!”

“Listen, I’ve been thinking about what you said yesterday about Dumpling’s weight loss,” said Joe.

Oliver nodded, and his smile faded.

“Well, I’ve been reading hamster books for my school project, and I found a chapter on health problems,” Joe continued.

“What do you think is wrong with him?” asked Oliver.

“I’m not sure. It could be a toothache. If you give your hamster too many treats, their teeth rot, and they can’t eat.”

Oliver gasped. “Will he die?”

“I’m dead already!” growled Dumpling.

Joe ignored Dumpling. “It might not be a toothache,” he said, seeing how worried Oliver looked. “So, I was thinking, Toby’s going to your house today, isn’t he? Well, maybe I could tag along and take a look . . .”

“That would be great. I’ll ask my mom after school.” Oliver grinned.

Dumpling’s face lit up with excitement. “I’m going home! I’m going home!” he squealed with delight.

Joe didn’t dare remind him that it wasn’t his home anymore and that it belonged to another hamster now!

At the end of school, Joe spotted Toby and Oliver at the gates. Oliver was talking to his mom. She looked concerned.

“Hey, Joe!” Oliver waved him over. “I was just telling Mom that you know loads about hamsters, and that you’ve offered to look at Dumpling’s teeth. Mom, would it be okay if Joe came home with us, too?”

“PLEASE! PLEASE!” Dumpling squeaked from inside Joe’s book bag.

“I’m really not sure . . . ,” Oliver’s mom said. It looked like a visit from a hamster expert was the last thing she wanted!

“Please!” Oliver begged. “You know how worried I’ve been about Dumpling lately.”

She sighed. “Oh, all right. But Joe will have to give his mom a call and check if it’s okay.” She handed him her cell phone.

Yes! thought Joe. He’d done it! He’d gotten an invite to Oliver’s house. All he needed to do now was work out how to prove Oliver’s hamster was a replacement. That was going to be a bit trickier . . .