The title “Boundary” refers to the K-T Boundary, an event 65 million years ago in which a large number of species, most famously including the dinosaurs, became extinct, probably due to the impact of a meteor. A group of paleontologists find a very strange fossil grouping, with bizarre anomalies including what look like bullets. The fossil sits right on the Boundary, meaning it is from the time of the event. A little later, the first mission (unmanned) to Mars’ moon Phobos reveals an abandoned, and ancient, alien base. The space program is accelerated to allow a large scale manned mission to Phobos and Mars.
This is the kind of adventure novel that I really love. Engineering, science, fun characters, and a great plot. A journey of discovery with a good sprinkling of old fashioned sense of wonder. It is not without its flaws, however. The dialog is often stilted. There is no deep exploration of interpersonal relationships as the characters mesh far too well. Love and friendship sprout in neat couplings and groups. I enjoyed this book a lot, but it could have had a bit more depth.