Nipper was furious at Samantha for making him leave all that treasure behind in the tomb. He couldn’t buy his Yankees or any other baseball team, and he was really, really mad. For a while.

Nipper wasn’t the kind of person who could stay 100 percent angry with anyone forever.

By the time he reached the center of the park, he was bored with being mad at his sister. He looked up at the art museum. The doors were propped open, and there was a noisy crowd inside. Some kind of event was under way.

Nipper reached into his pocket and took out the big blue gem. He tossed it in the air happily and caught it. Then he skipped up the museum steps, excited to show it off to anyone willing to take a look.

His foot slipped and he stumbled as he neared the entrance, but he caught the handrail and kept his balance. He patted the shape in his front pocket and kept going.

The lobby was packed from wall to wall with adults.

A group of men and women were playing banjos and accordions. All of them had oversized fake mustaches and wore badges that said Nasjonalmuseet. Whatever that meant.

He noticed the words Police du Louvre on the lapels of two women in gray business suits.

Many people were dressed like famous works of art. Someone walked by inside a giant soup can. Another person wore a clown costume.

Nipper saw a huge banner draped above the windows on the back wall.

STARCH

STOLEN TREASURES AND ARTWORK RECOVERY

CONVENTION AND HOEDOWN

A pack of men and women wearing bowler hats and green T-shirts with pictures of llamas pushed past him on their way to the door. Nipper turned and saw the words Seguridad de Machu Picchu on their backs.

Then he spotted a trio of men in togas standing around a huge punch bowl. They were handing out drinks and frosted cookies shaped like statues.

As he headed to the snacks, Nipper passed a man and a woman talking. He glanced at their attendee badges. The man was from Wahoo, Nebraska. The woman was from Wagga Wagga, Australia.

“If there were cows in here, this would be a MOO-seum,” said the man.

“Don’t arrest that painting. It’s been framed,” said the woman.

Nipper scratched his head and thought about the jokes. He remembered seeing the two names on the arches in the magtrain station. It turned out neither Wagga Wagga nor Wahoo was particularly funny.

Then he looked down at his empty hands. He looked down at his feet and at the floor around him.

The big blue diamond was gone!