The author T.C. Boyle in the preface to his book “Stories II” published last year made a convincing argument that runs counter to the conventional wisdom to “write what you know.” Boyle said: “A story is an exercise of imagination — or, as Flannery O’Connor has it, an act of discovery.”

Enter Mike Meginnis and his novel “Fat Man and Little Boy,” which takes the bombings of Hirsohima and Nagasaki as the nexus for an oddly impressive debut novel. The book follows the two bombs — the eponymous brothers who have been made flesh — as they grapple with the enormity of what they did, their earthly forms and what is to come.

Meginnis, 28, wrote the novel while completing a Master of Fine Arts graduate degree at New Mexico State University. His manuscript won the inaugural Horatio Nelson Fiction Prize, which earned him a publishing deal with Black Balloon Publishing. As his publisher’s biography notes, Meginnis has never set foot outside the United States. So this was a work of imagination. And research.

“Being open to being surprised and to discovering things that you wouldn’t expect is a wonderful way to get things in that you can’t make up,” Meginnis says of his research. “Stuff that’s happened is usually so much stranger than the things you make up — that’s sort of a cliche, but it’s true. If you were to make up what happened to people as a result of the bombs I don’t think you would believe it. I think you have to see the photos… So I think if you don’t use a lot of research in your fiction you are missing out on a lot of opportunities.”

Meginnis trawled through archival photos, documentaries and reportage in building a framework for his novel. Two books in particular were instrumental to Meginnis’ understanding of World War II in Japan, Emiko Ohnuki-Tierney’s “Kamikaze Diaries: Reflections of Japanese Student Soldiers” and Bernard Millot’s “Divine Thunder: The Life and Death of the Kamikazes” — especially in forming the character Masumi, a failed kamikaze pilot turned medium surrounded by ghosts, who can see the brothers for what they are: death.

The idea for the book came from a class about how war is depicted in film.

“There was an assignment where I went and read some old news weeklies like Time covering the week before and after the bombs were dropped,” says Meginnis.

The assignment awakened memories of the two bombs and their strange nicknames.

“Seeing these reports I immediately imagined them as brothers,” says Meginnis. “That was the intuitive leap I made.”

The brothers are united in the devastation of the atomic fallout. The novel straddles a hybrid genre of historical magical realism: There are obvious examples of real events, foremost being the obliteration of Hiroshima and Nagaski, but Meginnis keeps the focus on the two brothers; the harrowing aftermath could be anywhere.

“I definitely played fast and loose with some of the geography,” admits Meginnis.

One other image stayed with him while he wrote the book, one which will resonate with a lot of people in Japan: a scene from Studio Ghibli’s classic “My Neighbor Totoro.”

“You know the scene where they are waiting for the bus in the rain?” asks Meginnis. “I just immediately imagined Fat Man and Little Boy in that scene trying to share an umbrella, but they couldn’t because Fat Man is too big. That doesn’t happen in the book, of course, but that was sort of the image that guided the mood of the whole book for me.”

Fat Man and Little Boy are strange siblings and hard to like — they are conflicted and, like most brothers, nearly always in conflict.

“The point of connection (with the brothers) is the sense of self-loathing that they have,” says Meginnis.

Of the two, Fat Man ends up taking control, as Little Boy is stunted, both physically and mentally. They hatch a plan to obtain forged passports and escape Japan, and their responsibility for its destruction — although you wonder what they could have done in atonement. What could anyone do after that?

The novel, despite its themes or because of them, is not without its humor, such as when the two brothers discuss where to go after Japan.

“Why France?” says Little Boy.

“They were barely in the war, and the food is supposed to be good.”

“Does it always have to be food?”

In France, Matthew and John, as the two bombs are called, fall in with a host of characters, chief of which is Rosie, a war widow who opens a hotel on the site of a former concentration camp and whose aim is to encourage multilingualism as the ultimate deterrent against war, as well as the aforementioned Masumi.

The strength (and weakness) of Meginnis’ book is in his language, often lucid, sometimes lurid and sometimes oblique. Through Fat Man and Little Boy the reader is forced to reckon with what these brothers have done.

“In a lot of ways (the book) is about shame,” says Meginnis. “For me it’s more about the feeling of being implicated in something terrible, and how you live as a person who is a part of a culture that has done terrible, frightening things and how you live with your personal responsibility in that suffering — and how you know where it ends.”