Floyd visits Halley's Comet, then sets off to rescue his grandson, who was crew of a ship that crashed on Europa.

This installment in the series was a bore.  There was no point to the exploration of Halley's Comet, especially as it was done in such a shallow manner -kind of like Kevin J. Anderson does with Star Wars books.  And we are given the hint that there might be life there, too.  The stuff on Europa was bland, though there were a couple of interesting twists.  The "mystery" of the diamond mountain was not well done, as the references to the diamond consortium were vague to those who don't know it.  And wasn't Chris the main character's son, not grandson, in the last book?