Unexpected Visitor

Mur has kept a secret under his floorboards for fifty years.
He was twelve when his best friend's mother handed him a strange box and made him promise to hide it. That evening the family drove away, their house burned down, and Cleo never came back. Mur grew up, went gray, and became the handyman every small town needs. The box stayed where he put it.
Then, in a single night, two visitors come for it. One steals it and vanishes. The other is Cleo. Fifty years have passed, yet she looks like she is just twenty-five.
She is going after the thief, and the spaceship parked outside his house was not built on Earth. A sensible man would stay home. Mur asks if there is room for one more.
He waited fifty years for the girl to come back.
Nobody told him the galaxy would come with her.