In this 7th novel in the Tom Swift Invention Series, the planet Pluto suddenly disappears. It is there one minute and gone the next. Is this the start of an invasion, or something even worse? Tom Swift is called upon to investigate. For starters he agrees to refurbish and move the long-defunct Hubble Space telescope into a position where it might scan the now empty area. Finding nothing he builds an ultra fast space probe. But when that disappears...