They're all immune to HLV...until they aren't.
When a mysterious illness breaks out at the armory, Grace and the others scramble to save everyone when it becomes obvious HLV has mutated again. Jason, a recent arrival, knows of a research facility that might hold a cure, or at least a vaccine, so she and Clint go with him to see if they can find a way to save their people. Rafe joins their group after he steps in to save them at one point during their perilous journey, and she's drawn to him as well. Can the four of them find a way to stop HLV before it kills more people, while also building a relationship strong enough to survive Clint, Jason, and Rafe sharing Grace?
This is a reverse harem romance and the fourth in the Hell Virus series. It can be read as a standalone, but reading the series in order will give a more complete and enjoyable experience.