You need to pick up one of those magnifying glasses. Oh, and a trenchcoat. You want to close cold cases and fight crime, so those must be mandatory, right?

Trenchcoat, magnifying glass, catch killers, solve crimes – that’s what it takes to be a P.I. Or you need to read “Becoming a Private Investigator” by Howie Kahn.

No big surprise: your favorite TV detective show has everything wrong.

On television, the P.I. is usually looking for a murderer. In reality, Kahn says, private investigators deal with a variety of issues that need deeper research than perhaps most people are able to do.

On television, P.I.s are always broke. In reality, they make up to $500,000 on bigger jobs. TV crimes are solved in an hour, minus commercials. In real life, a private investigator might work on a case for years.

If you think it’s a career for a person with patience, you’re right. Private investigators are research experts and can unravel the most knotted facts. They’re also flexible and know how to read people.

They’re also good at “disrupting” stalled investigations, a talent police sometimes hate. P.I.s are able to think sideways to spot clues and have the tenacity of 10 terriers.

As for the industry itself, Kahn cites Bureau of Labor Statistics that predict an “occupational growth rate” of 11 percent which is much higher than for other jobs.

Three years ago, the U.S. boasted more than 40,000 working private investigators, all of which, presumably, are licensed, since the majority of America’s states have strict requirements on licensure.

To give readers an idea of what it’s like to work as a private investigator, Kahn followed two P.I.s, one in Tennessee and one in Texas.

The former became a private eye after helping to solve the murder of her former roommate. She wanted to quit when it was over until she realized that her expertise was still needed. The Texas P.I. gained his skills while in the military, and he shares with Kahn a case that still dogs him

Readers who come to this book for career advice will be quite surprised at “Becoming a Private Investigator,” for two big reasons.

While this series of guidebooks is generally meant for high school students and adults looking for career changes, this one focuses almost entirely on the latter. Indeed, both private investigators profiled are older adults who started their respective careers well past their high-school years.

Yes, teens will glean information here but adults will benefit more.

The other truly pleasant surprise is in the true-crime elements in which this book is so deeply steeped.

Kahn’s investigators and their case studies will call to mystery mavens and armchair detectives alike, perhaps aiming crime solvers toward fascinating second careers later in life.

Even if you’re not swapping careers, this different kind of business book is pure fun to read.

If you’re thinking of a new job, however, and need help launching, get “Becoming a Private Investigator” and magnify your options.

Terri Schlichenmeyer’s reviews of business books are read in more than 260 publications in the U.S. and Canada.