Our story begins with a startling announcement: that Father Emilio Sandoz not only traveled to a foreign world, but is also the sole survivor of the expedition. Then, little by little, we learn what brought them to Rakhat in the first place. We learn how Sandoz met the others who'd eventually travel with him. And we anticipate their demise, already knowing Sandoz travels home alone. 
 It's the non-linear storytelling that sells this one to me. This would not be the same story if told chronologically--the expedition is told in flashbacks, interspersed with the "present-day" events (or, the year 2060) of Sandoz's healing and trial. We learn early on that the mission is a failure, but still cling to the irrational hope that there will be some kind of success in the first interplanetary travel. 
 For being a secular book, it handles God wonderfully. It's the Society of Jesus who sends Sandoz & Co to Rakhat, but even Sandoz himself isn't the most perfect priest. He views the trip as a mission from God, but struggles with his faith the more time he spends on the foreign planet. The man is brilliant and personable; everyone he meets loves him. But he holds secrets, and it's those secrets that give his character depth and make him something more than simply a "perfect priest" character. 
 I'll admit, it took me about halfway through to really get into the story. The other characters have depth and personalities, too, and there may be too much unnecessary backstory for some of them. I'm still not what what the deal with Sofia Mendes is, but I didn't really have to get it for the sake of the story. But once they're on Rakhat, their connections feel more genuine. You care more for them. Or maybe that's because you know they're all going to be dead. 
 There is a sequel, which I may pick up at some point. But even with a semi-opened-ended conclusion, this one is fine to stand on its own.