So, that was an incredibly intense, fantastic read. It will not be for everyone because it focuses on some darker issues of a post-apocalyptic society, including dubious consent (bordering on non-consent in the mind of at least one character). 
 In this case, a virus intended for biological warfare was mishandled and released to the general populace. A few batallions of soldiers were infected with the Alpha strain, increasing their speed, stamina, and strength. It was designed to mutate into the Beta strain when their blood was exposed to air (presumably upon their deaths), and then have a slow gestation period so that the carriers would take it back to their headquarters and pass it around before it became visible, manifesting as bruising. It was supposed to make their enemies lethargic, but it was rushed out and actually made them Rot. 
 But in some of the population, it became the Gamma strain, which turns the hosts into ravenous, semi-sentient beasts, which have come to be known as revenants. (Firefly/Serenity fans will notice the resemblance to the "Pax" and the Reavers at this point. That's where the resemblance ends, though.) However, those infected with Alpha are immune to Beta and Gamma. 
 We start the story seven years post-infection as a pack of revenants has entered a monastery where some humans have been hiding for many years. Though the others die, Rhys and Jacob live. Jacob is a smarmy, cowardly, thinks-he's-charming-but-he's-an-asshole bully who was the son of the preacher leading the group. He ran away from the revenants instead of protecting his wife (Rhys's sister, Cadence/Cady) and newborn son. Rhys was voted to be the one to sacrifice his life by leading the revenants away from the others, and he did his best to save his sister and nephew, but it wasn't enough. 
 The Alpha soldiers, known as Juggernauts, which happen upon them just after the bloodshed begins, manage to save just the two of them, but suspect both have been infected. The only way, theoretically, to save them is to infect them with Alpha, but Alpha infection is only known to have occurred through sexual transmission, and no one's ever tried to use it to beat Beta or Gamma from taking hold, so there's no telling if it will work. They may still die anyway. And if they live, they will never be allowed inside the human safe-zone colony; Juggernauts can still pass on Beta if they're bleeding, so they cannot be allowed to stay around regular humans on a permanent basis. If they become Juggernauts, they will remain with the Jugs for the rest of their lives. 
 Death or possible exile as a Juggernaut. Those are Rhys and Jacob's only choices. But to become a Juggernaut, they have to have sex constantly with all of the willing men in the group, to be exposed to as many variations of the Alpha strain as possible. For Rhys, this is traumatic; it is everything that he was taught sex isn't supposed to be. Sex is supposed to be about intimacy, not life-or-death, thus there's no pleasure in it for Rhys, even though it's necessary. He's gay, but he doesn't want to be forced for the wrong reasons, no matter that he could die if he doesn't. But, he doesn't want to die either. 
 Does that make it rape? There is definitely a huge question in some minds about whether or not the sex is consentual. Rhys doesn't want to be forced into sex, because that's not what sex is supposed to mean, but because he doesn't want to die, he looks at being forced into sex as saving his life, and he is grateful for that. He doesn't view it as rape. However, because he is so miserable due to the situation and having to endure the sex, he makes those around him who are willing to help save his life feel as though it is rape because of how unhappy he is. 
 The only time he's not miserable is when he's with Darius. The fact that Darius gives him no control or choice in the matter frees Rhys from some of his mental shackles. (There is dominance and control exerted, but it's not in a typical modern-day BDSM power exchange. It's more feral than that due to the circumstances and change in the world.) 
 The only downside to sex with Darius is how vocal Rhys becomes, which is bad because Jacob will use that against Rhys to verbally abuse him. Jacob's also becoming more sinister and aggressive towards him because the squad likes Rhys more than they like Jacob. 
 There are lots of other difficulties which Rhys has to face when the group runs across a survivor whom both Jacob and Rhys know from years ago at the monastery; when Jacob eventually becomes a Juggernaut, but Rhys still does not; and when Jacob eventually takes matters into his own hands. 
 The story sports a superb cast of characters. We get to know several of the squad which rescued Rhys and Jacob before they get back to the base. Joe's backstory was the most interesting and relevant. I liked Xolani and Titus a lot as well. 
 The story is told from both Rhys's and Darius's point of view, so we really get into their heads and understand why they feel the way they feel, which is important to the story and its impact. 
 As for the end, it left open the possibility for more in this universe. There are still unknowns about the virus and how it operates; things didn't exactly happen as Xolani hypothesized they might. The question remains: what now? 
 This is definitely worth the read if you can be open-minded about the control and consent issues presented and look at them through the eyes of a post-apocalyptic society instead of with modern-day sensibilities. Highly recommended.