Changes

|publisher=Simon and Schuster

|date=August 2012

|summary=Amusing galaxy-crossing antics for two children, as Earth needs saving by them for a second time. This has reasonable comedy, but the drama is above average.

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On a school trip to an observatory, a scientist is being very stupid and silly in trying to impress the class of visitors about his work, which is very ironic considering what will happen to two of them. When the session leads to the discovery of an asteroid on its way to collide fatally with Earth, Lance and Tori are shocked to see the evil lizard they had to defeat in the first book in this series being asked for help. Soon they have to enter a cat-and-mouse chase across the very galaxy the scientist was so uncool about, to save the planet - and, as the title says, Lance's sister.