Sheridan understands that what he is doing is more than a little bit out there. He does not really expect the world to end. And if something does go terribly wrong — a tsunami, a nuclear attack, a huge earthquake — he does not really believe that human empathy and common decency will suddenly disappear. The big box office chaos of a postapocalyptic world does not match human experience. It did not happen after Hurricane Katrina in New Orleans, it did not happen in Haiti after the earthquake, and it did not happen during the 2003 New York City blackout.

“Group panic,” Sheridan writes, “needs certain distinct, extremely specific factors to occur.” Without those specific factors — none of which would be present following a disaster scenario — people reorganize. Society adapts and regroups. The every-man-for-himself fight club life that he prepares for is simply not what he expects.

But that takes none of the enjoyment out of his training. From the beginning, Sheridan understands exactly what he is doing. He is giving readers a fantasy ride, imagining, for amusement’s sake, that training for the end might be worthwhile, that the father’s job may someday be to protect and provide, and to do so heroically. And clearly, he enjoys the ride himself, savoring every moment, both physically and intellectually.

On first blush, one might be tempted to groan about The Disaster Diaries to bemoan it as a macho ego trip, a testosterone-driven romp to nowhere. But that would miss the point. And that point: Postapocalyptic heroism, in the hands of Sam Sheridan, is just plain fun.

Bill Streever reviewed this book for The San Francisco Chronicle.