When Charlotte's parents leave her with her nan, she is dismayed that her grandpa is no longer himself. Then she encounters a strange boy in her grandfather's old bedroom. Who is he and what does he want?
As Charlotte gets to know Keith, he sweeps her up in his excitement about the astronauts soon to land on the moon for the first time in history.
But as their worlds become entangled and Charlotte slips back and forth in time, she realises she is changing history, and she starts to be afraid. Will something she says, or does, bring disaster on the moon landing?
And can Keith and his enthusiasm help Charlotte reconnect with the silent old man in the nursing home?