In this 16th novel in the series, Tom is informed by the company's Observatory that a planet outside the orbit of Pluto is now definitely proven to be there, but there is a problem. The repeating cycle of Haley's Comet will bring it inclose encounter with the new planet. So close, in fact, that it is impossible born an Earthbound point of view to not know for certain if they might not collide.
A new space telescope soon sees just how close it might be, and when numbers are crunched it looks as if any near pass will influence the comet in such a way that it could swing into a dangerously close pass with the Earth.
At millions of miles farther out than Pluto, it will either take far too long to travel out to see what is going on, or it will take a radical new form of spaceship propulsion.
And, guess which one Tom Swift goes for?
Once Tom and his small crew arrive it is to find that there will be no close pass by the comet and the small planet Eris. It it a full on collision that starts to break up what they find to be a very fragile planet.The race is on to try to pull things back together before everything heads in toward the sun and eventual passes with Mars and the Earth.
The biggest issue is, nobody has ever tried to put a planet back together!
