The Paradox of the Sets

Stableford finishes his Daedalus planetary exploration series. As with the other books, there's a puzzle to solve involving the colonists and a local species called the Sets. In addition the book also resolves the issue that triggered its 5 year mission to re-establish contact with colonies from 150 years before and perhaps re-kindle stellar exploration. There's some trekking back and forth and an extended adventure underground, with an explicit nod to Verne. There's also an awful lot of debate and conjecture. While the series wraps up loose ends satisfactorily (no spoilers here), it never really gains any serious heft or momentum, and you never care about any of the characters that have been around for 6 books.