When a boy called Keith pops up from nowhere in Letty''s bedroom and accuses her of invading his room, Letty is astonished - but things get even stranger when she realises she is caught up in an incredible adventure, able to slip back and forth in time!Keith lives in the world of 1969, and Letty joins in the thrill and excitement of the first astronauts about to land on the moon. But when she discovers her trips to the past are changing history, she starts to worry. What if something she says or does causes a disaster - or even messes up the moon landing?