Even though Justin Cronin writes about vampires wreaking havoc in a postapocalyptic world, what he’s really interested in, he says, is exploring human relationships. The Passage, a 2010 release that was one of the most talked-about books at that year’s BEA, is “very much a novel about people in a familial structure,” as groups of humans fleeing the vampires who’ve taken over band together into communities and attempt to recreate some semblance of normal life for their families. Cronin is particularly interested in how relationships between parents and their children evolve in such a setting because, he explains, “If you are writing any book about the end of the world, what you are really writing about is what’s worth saving about it.”

It should come as no surprise that children often take center stage in Cronin’s trilogy. After all, the story line of the trilogy was conceptualized during a series of after-school conversations between Cronin and his daughter, now a teenager, who was eight years old at the time. “We were playing a game which if it had a name, would have been called ‘let’s plan a novel,’ ” Cronin recalls. “We were just having a good time together, but as we did this every day, a really, really great story emerged. One character [Alicia] had to have red hair because my daughter is a redhead.”

The Passage, The Twelve, and the third novel in the trilogy, which has a working title of City of Mirrors, remind Cronin of the kinds of books he enjoyed when he was his daughter’s age. “I was very much a child of the cold war,” notes Cronin, who is turning 50 this year. “And I grew up on a steady diet of science fiction, especially apocalyptic and postapocalyptic fiction.” Such literature, Cronin contends, has a long and proud tradition in the literary canon, going all the way back to the biblical account of Adam and Eve being expelled from the Garden of Eden.

“It’s a way to grapple with the temporary nature of human life, the fragility of the human species,” Cronin says, referring to the biblical story of Noah’s ark as God’s “do-over,” when one family survived the great flood. “It’s a way of saying that family bonds strengthen the survivability of the species.”

The opening chapters of The Twelve return readers to the year zero and “reset the terms of the story,” Cronin says, providing readers with information they weren’t given in The Passage, thus taking the narrative in a different direction. While Cronin admits that the title could refer to the original 12 convicts who became virals in The Passage, he insists that there are multiple meanings to that number. “It’s a heavy, freighted word in the trilogy,” Cronin declares.