The Smith family prepared for every eventuality including a zombie apocalypse, although that was mostly for entertainment purposes. So when Steve Smith, husband, father of two teenaged girls, and high school history teacher receives an Alas, Babylon code from his brother indicating an actual zombie apocalypse he calmly informs the school of a family emergency and walks out. Someone has engineered a virus that causes people to strip naked just before they lose all higher brain function and are reduced to basic animalistic urges. While most of the world is trying to contain the growing population of naked maniacs the Smiths load up a sail boat and work with a team making an ethically questionable vaccine. After a couple of months at sea they're running low on supplies so they board a slightly larger ship and eliminate the remaining "zombie". They also find a terrified teenager barricaded in her cabin which sparks something in the Smiths. They have guns and the guts to clear the Atlantic of zombies one ship at a time and save as many people as they can.

John Ringo has a real feel for human nature. In between the zombie action scenes there are the ethically hard questions, dark humor, and scenes that might have seemed more ridiculous before the COVID-19 pandemic. The first half of the book is largely focuses on the government's efforts to contain and treat the new disease. While the CDC and experts around the globe are trying to work on treatment and a vaccine the FBI is looking for the culprit and how they are spreading the infection. Ringo points out the FBI's less than stellar track record with biological threat investigations and the dialog between the CDC and the FBI agents is hilarious. There is a lot of biomedical jargon in this section, which might be confusing for those who don't have a degree in microbiology and background in research. In the meantime fifteen year old Sophie is working in an illegal vaccine production lab while thirteen year old Faith is excited to be killing her first zombies. This first half doesn't feel slow and plodding thanks to the humorous commentary and much of it parallels the reality of COVID-19 although it was written several years earlier.

The rest of the story takes place on the Atlantic Ocean as the Smiths start going from one emergency signal to another in the hopes of survivors and supplies. There is a mix of action, humor, and tragedy in what they find. The saying "what happened in the compartment stays in the compartment" refers to the various difficult choices people faced to survive as well as the very high percentage of rescued women that are pregnant. Some of those they rescue join them in their crusade to take back the world one ship at a time including a retired Green Beret and a young Marine. There are many small stories of minor characters surviving the apocalypse. Some funny, some horrible, but they are all very human. In this half Aussie, military, and gun jargon is prevalent. Fortunately, there is usually a character who eventually asks what a phrase means, but it might be several chapters after it first appears.

I don't normally go for zombie apocalypse stories but I'm very glad I took a chance on this one. Its an addictive soap opera that balances action and fun with stories about people under pressure. Ringo's description of human response to a pandemic were only validated by the real world response to COVID-19. The writing is excellent and although there isn't much development of the three main characters the many supporting characters provide plenty of unique stories. Naturally, much of the story involves fighting zombies and the action has plenty of detail.

Under a Graveyard Sky is available in all formats. The audio version is only available from Audible and narrator Tristan Morris has a 4.5 star rating. There are several more books in the series and some anthologies of short stories from various authors set in that world.