“Collins, steer us manually,” Bridget-as-Buzz ordered. “Over these boulders into the Sea of Tranquility.”

“We’re landing in a sea?” asked Sally Ride, clutching the handrail so hard her knuckles had gone white. Maybe she was motion-sick. Or afraid of heights. Nova wished she could tell her it was okay. Bridget always managed a soft landing.

“It’s not a real sea, right?” asked President Nixon. “That’s what Armstrong named it after they landed.”

“Right,” confirmed Bridget-as-Buzz. “There’s no water on the moon, not that we’ve ever found, anyway.”

“Oh,” said Sally Ride.

“We only have thirty seconds of fuel left,” said Bridget-as-Buzz. Nova closed her eyes and braced for impact.

“We did it!”

Nova opened her eyes, relieved. Even though she trusted Bridget, the landing always made her nervous.

“Armstrong, tell Ground Control, ‘The Eagle has landed.’ ” Bridget lowered her voice. “Nova, that’s you…Say ‘The Eagle has landed.’ ”

“Uh Ego ah lah-dah.”

Ground Control and the Nixons applauded. Checkers barked, wagging his tail.

“Take the flag,” Bridget-as-Buzz said, thrusting some leaves attached to a long, skinny twig into Nova’s hand. “Go plant it down there on the surface and say, ‘That’s one small step for a man, one giant leap for mankind.’ ”

Cautiously, Nova-as-Armstrong made her way down the ladder to the moon’s dusty white surface. She planted the flag in the ground, making sure it was standing up straight.

“Uh mah tep,” she said proudly.

President Nixon saluted.

Nova-as-Armstrong was making her way back up the ladder serenaded by cheers and happy barks from the crowd below when a sickening creak stabbed her through the stomach. She stopped breathing.

The rotting wood floor of the back room of the tree house was giving way. The boy playing Collins leapt forward into the first room, but Bridget didn’t have time to grab for the railing or even one of the nearby branches. She fell hard through the rotted wood and landed on her elbow. When she stood up, her arm was bent the wrong way. Backward.

“Mission accomplished,” she announced, grinning. She looked down at her floppy busted arm, then at the flag Nova-as-Armstrong had planted on the moon’s surface.

She didn’t even cry.

After she got her cast, she let Nova be the first to draw on it.

Nova drew the moon, because they’d made it.

When Bridget was in charge, they always made it.

With Bridget gone, Nova would have to try to make it on her own.

She had one hour before it was time to get ready for school.

One hour.