Eric Flint and Ryk Spoor’s THRESHOLD is a space opera that centers around our near-future Earth, Mars, and a bunch of long-lost alien artifacts.  (The first book, BOUNDARY, while a good read in its own right, does not have to be read in order to understand THRESHOLD.)  All you really need to know to start this book is that the human race has attained space and now has a small colony on Mars, and that there’s a hope that more alien artifacts (of the type found on the Earth itself and Mars during the course of BOUNDARY) may reside within the solar system.

THRESHOLD starts out with a quick recap of what has gone before (deftly incorporated into the narrative), which is this: Madeline Fathom, formerly an agent for Homeland Security, has resigned to take a new position on Mars along with her new husband, Joe Buckley.  Helen Sutter, a paleontologist, and her much-younger husband, A.J. Baker, continue to puzzle out the alien fragments left behind that have been named Bemmius Secordii for two reasons: “Bemmius” is for the “bug-eyed monster” the aliens apparently looked like, while “Secordii” is the name of the person, Jacqueline Secord, who discovered the alien artifact in the first place.

Because of the alien artifacts, humans have finally been able to get out into space to stay.  (Human ingenuity plus alien knowledge is the equation Flint and Spoor make, and quite credibly, too .)  Now, there’s a legitimate “space race” going on, with India developing a “space elevator” for freight, the European Union building the biggest, baddest spaceship on record (the Odin), and of course Baker’s own Ares Corporation (the first private company in space, headquartered on Mars) also develops its own, small spaceship.

Over time — as much of this story is told in the form of vignettes — Fathom and the others realize there’s a real problem: the Martian artifacts, which have been freely shared with the crew of the Odin, lead to yet another artifact.  The Odin’s crew, rather than telling everyone on Mars (and Earth) what they’re doing, instead cuts the Martian colony completely out of the equation, possibly so the EU will be able to put its own, massive footprint in space.

While the devious nature of the Odin is not in question, there’s a further problem.  The Ares Corporation has far more work than it knows what to do with considering the alien artifacts known to be on Mars that are within its purview (as most of Mars has been parceled out to other Earthly concerns, if and when they are able to join the United States, the EU, and other major groups in space), but Fathom, a security specialist, does not believe the Odin should be left to have it all its own way.   To be blunt, she emphatically distrusts the Odin’s chief of security, Richard Fitzgerald, because he’s more or less amoral — she calls him a “mercenary . . . sociopath,” which may or may not be true.

What is true, though, is that Fitzgerald is the most unscrupulous crewman on the Odin.  Fathom is right to distrust him, as is the Captain of the Odin, General Hohenheim.  And what Fitzgerald will do to try to gain the Odin an advantage may just start the first — and, possibly, last — interstellar war.

THRESHOLD is an excellent book that does everything right.  There’s treachery, politics, love, mayhem, friendship — in short, the usual array of human personality traits and emotions — which just goes to show how well grounded Flint and Spoor are in human psychology.  All the relationships (positive and negative) make sense in context, the science (both the alien and human) seems sound, and the story is well-constructed.

But be warned: as the name THRESHOLD suggests, this story leaves the reader on tenterhooks, especially in the latter half of the book.   (Especially with regards to this question: will Joe Buckley survive?  Or won’t he?  Tune in tomorrow . . . . )

That being said, there is a sequel to THRESHOLD in the works called PORTAL (Spoor’s Web site mentions that PORTAL was accepted by his publisher, Baen Books, last September).  This is a very good thing, because THRESHOLD asks more questions than it answers and left most of “our heroes” in a devilishly tight spot.

So, you have an episode in a very good space opera series, with another to follow.  Excellent!  (Put me on the list to read PORTAL soonest, please.)

Grade: A.

— reviewed by Barb