We’ve all had the misfortune to come upon a suspicious package while on patrol. Most of the time we see it for what it is: a forgotten briefcase or school bag, a suitcase thoughtlessly left behind on a subway platform, or a gift box left at an intersection when the red light took too long to change. Occasionally, it’s an object designed to look like an explosive device, and on even more rare occasions, it actually is a bomb. And when that happens, it’s the NYPD’s 103-year-old Bomb Squad’s job to determine the relative risk of the device and to disarm it.

Clearly, this is not a job for everybody.

Whenever I was on a job and the Bomb Squad appeared on the scene, I always found myself wondering — while getting far away from the object as possible — who are these guys and why would they want to do that job? The answers are in a new book, “Bomb Squad,” by Richard Esposito and Ted Gerstein.

Their portrayal of this group of law enforcement pros will surprise many. Bomb squad technicians are not, as some people believe, cowboys or reckless thrill-seekers. They are highly skilled, intensely disciplined men with nerves of steel seeking to prevent harm to innocent people. They practice their craft like a religion and worship at the altars of information, expertise and experience. They rely on a network of like-minded technicians around the globe who provide quick, accurate intelligence about new improvised explosive devices (i.e.d.s). Knowledge is the life-blood of the Bomb Squad.

Esposito and Gerstein were granted unprecedented access to the squad for an entire year. They started their research on December 31. 2003 and spent a year rolling on jobs with the squad and learning about its successes and failures. The book is a fascinating mix of the squad’s history and personal profiles of the men who don the Kevlar suits today to disarm explosive devices. The book also contains a dose of NYPD politics that will ring true to the ears of any MOS who reads it.

It’s easy to believe the stereotype that Bomb Squad guys are in your face, afraid of nothing, macho guys — that they are officers of great courage but very probably insane. It makes for great movie characters. But movies are not reality and after reading the book, it is clear that they are stereotypically courageous but far from insane.

Admittedly, they are technical fanatics, constantly reviewing technique and avidly seeking new information on i.e.d.s, which we have come to know as the leading cause of U.S. casualties in the Iraq war. The book reports that a worldwide “brotherhood of the bomb” exists to share the latest information on devices. The moment a new i.e.d. is discovered or detonated, the news travels to bomb squads around the world, including information on how it was built, detonated and how best to disarm it. Information is the bomb squad technician’s best anti-bomb defense. When they approach a device — slowly and carefully — technicians want to be armed with as much knowledge as possible. For a Bomb Squad tech, surprise is often deadly.

The worldwide intelligence is essential to the prevention of terrorist bombings. That intelligence gives squad members the signatures for the bomber and the device and the information is often used to prevent a bomb from being planted or carried into a target. Whether it is a device carried onto a bus in a backpack or a pipe bomb left on the street, the book stresses that the point of a bombing is to spread terror. Early intelligence allows the NYPD to prevent plantings and detonations. Any Bomb Squad tech would much rather see a bomb prevented from being planted than to have to disarm it — a sane preference, if there ever was one.

All New Yorkers, sworn police officers and civilians, should be deeply grateful for the NYPD Bomb Squad and to Esposito and Gerstein for bringing us inside their world.