Hi! I’m Mimi.

This is Lulu.

We look alike because we’re twins.

This is our big brother, George.

George is in fourth grade.

George used to play with us.

But now he says, “Why would I want to play with baby toys?”

We like playing with George, but we understand.

He’s very grown up.

He has important things to do.

One morning, when Lulu and I woke up, we had a surprise.

Our nice, clean room was a mess!

There were marbles rolling all over the floor.

At breakfast, George noticed that Lulu and I were unhappy.

“What’s wrong?” he asked.

“Someone messed up our room while we were sleeping,” I said.

“And we had to clean up the mess,” Lulu added.

George nodded.

“It’s probably the monster in the hall closet,” he said.

Lulu was scared.

“Is there really a monster?” she asked.

“Sure,” said George. “It sneaks in at night to play. That’s what monsters do.”

After breakfast, Lulu and I went back to our room.

We needed to make a plan.

“I don’t like monsters,” Lulu said.

“There is no monster,” I said. “George is just trying to fool us.”

“I think it’s Cosmo,” I told her. “Cats like to play at night.”

“Maybe,” said Lulu. “But it could be a monster.”

“All right,” I replied. “Let’s build a monster trap. We’ll catch whatever’s making the mess.”

“Yes!” said Lulu. “But how?”

“We can use a mousetrap,” I said. “We’ll catch it by its toe!”

Lulu frowned. “I don’t want to hurt the monster. Let’s think of something else.”

We needed a trap big enough to catch the monster, and strong enough to hold it.

Could we catch the monster in a box?

Could we trick it into falling in a hole?

Could we scoop it into a net?

We drew pictures of many different traps.

We looked all over the house to find stuff to build a monster trap.

Here are some things we decided to use.

“The laundry basket is big enough to catch the monster,” I said.

“The ruler can hold the basket up,” Lulu added.

“The monster likes marbles,” I said.

“Yes!” said Lulu. “If we put marbles under the basket, the monster will go there to get them.”

“But what will make the basket fall?” Lulu asked.

“We will!” I told her.

I tied the string to the ruler.

“We’ll stay awake,” I said. “When we see the monster, we’ll pull the string. The basket will fall and we’ll catch that mess-maker!”

When we were done, here’s what our monster trap looked like.

That night, we got into bed and held on to the string.

We waited for the monster to sneak in.

But then we fell asleep.

When we woke up, the laundry basket had fallen down.

It was empty.

“Oh, no.” Lulu said. “That sneaky monster got past us.”

“It was a good plan,” I said. “If only we could stay awake.”

“I have an idea,” said Lulu. “We’ll get the monster to wake us up!”

Lulu ran out, then came back with a handful of round, jingly Christmas bells.

She mixed them in with the marbles.

That night, we set our trap again.

We got into bed holding on to the string.

We fell asleep.

Suddenly, in the dark of night… DING! DING! DING! DING! DING!

The bells were ringing.

Someone was in our room!

I snapped on the light.

There was George, holding a handful of marbles…and bells!

“It wasn’t a monster,” Lulu cried. “It was you!”

George hung his head.

“There’s no monster in the closet,” he said.

“You said our toys were for babies,” I said.

“I guess I was wrong,” George replied. “I still like to play with them sometimes.”

Now George and Lulu and I all play together.

And we’re very glad to know there’s no monster in the closet.

THE END