“Bags Fly Free.” The three magic words, splashed across Southwest Airlines’ promotional materials, sounded like a sweet deal to Ambre Boroughs as she boarded a return flight from Chicago’s Midway International Airport to Charleston International Airport.

On Boroughs’ initial flight to Chicago, the cabin had been packed to the gills. With no space for her laptop bag in the overhead compartment, she had endured an uncomfortable flight with it either on her lap or under her feet. Before getting on the flight back home, she decided she would take Southwest up on its offer: Every passenger’s first two bags fly free, as long as they weigh under 50 pounds and are no more than 62 inches in size (length plus width plus height).

“I felt a little bit nervous about it, but not really,” Boroughs says. “I figured if something happened, it would be handled.”

As the office manager at Palmetto RV in Mt. Pleasant, Boroughs uses her personal computer to handle customer invoices and sensitive employee information including Social Security numbers. She cannot afford to lose her laptop.

So when Boroughs picked the computer bag up from the baggage claim conveyor belt in Charleston late at night on March 27, she was shocked to find her laptop was missing. She rushed to the Southwest Airlines kiosk, but the attendant seemed uninterested in helping her out. Hers was the last flight of the evening, and the worker was about to go home.

“She very quickly told me that Southwest did not cover laptops,” Boroughs says. “She said, ‘Why would you check your laptop?'”

As it turns out, the attendant was right: If you leave your laptop computer in checked baggage on a Southwest flight and it is somehow damaged, lost, or stolen, the airline will not pay to have it fixed or replaced. The same goes for jewelry, cameras, personal documents, collectibles, and all fragile items.

Boroughs was frustrated to find the lengthy list of exceptions buried on page 26 of Southwest’s 33-page Contract of Carriage, a document she never saw before purchasing a ticket or checking her bags. Waking the next morning, she called Chicago police to see what could be done.

“I filed a police report, but it was pretty much like, ‘You’re screwed,’ ” Boroughs says. “Who cares about a laptop in Chicago, right?” After talking with cops on the Midway Airport beat and explaining that she figured the computer had been stolen, she took matters into her own hands. She used her smartphone to pull up the electronics page on the Chicago Craigslist, searched for her computer’s make and model — HP 9000 — and started hitting the Refresh button like a madwoman.

“My roommate said, ‘You’re crazy. You’re never gonna find it.’ I was like, ‘Screw this, they’re not going to get away with this,’ ” Boroughs recalls. “‘Somebody’s gonna have to pay for this.'”

And pay they did — but not until Boroughs had done a little undercover work. She finally found a listing for her laptop on Craigslist. She knew it was hers because of a sticker she had put on the cover for local punk band the 33’s. The band’s members were longtime friends for whom she had booked shows for years in her previous profession as a Charleston music promoter. She got the seller’s phone number and sent a text message.

“I said I was interested in his computer, and he said, ‘Which one?’ ” she recalls. “I said, ‘How many do you have there?’ He said, ‘Ten or 15.’ ”

The man on the phone told her the price was $350 for the one with the sticker on the cover, and he said that the hard drive had been wiped clean.

Keeping her cool, Boroughs took steps to make herself believable. She said she was in Chicago visiting family (hence the out-of-town area code) and that she was staying in the far-off Bucktown neighborhood, so it would take her a while to get to the Midway area. She even talked him down to a price of $300 (She had bought the computer for $850 in January).

Immediately afterward, she called the Midway police again and got a hold of Commander Thomas Argenbright. She told him the details and the address, and a detachment of officers sprang into action, driving over to the house where the deal was supposed to go down. As soon as a female officer posing as Boroughs bought the computer, the rest of the cops poured in to raid the house. They found it chock full of computers and jewelry and arrested the husband and wife living there, as well as their adult son. None of them worked for Southwest.

“She did a good job, and we need more citizens to be aggressive like that,” says Argenbright, who is the head of security for both Midway and O’Hare.

Argenbright says checked-baggage thefts are down in recent years; the 77 thefts reported in 2010 represented the lowest sum on record for the two airports. But Boroughs got the sense that it was an epidemic. As she searched online message boards for other people who’d had their belongings stolen, she found hundreds of complaints from both Chicago airports and from around the country. Many had flown Southwest.

Boroughs took another Southwest flight to Chicago in October — this one on the airline’s dime, she says — to testify in court about the theft. Of the three people arrested, two had their charges dropped, while one pleaded guilty to a misdemeanor theft of lost or mislaid property. Ultimately, the court was unable to prove the other valuables had been stolen because Southwest did not have theft complaints for them on file.

Nathaniel Irvin, lead vocalist for the 33’s, says the whole incident was “pretty damn hilarious” and a small publicity windfall for his band. When the Huffington Post picked up Boroughs’ story, the news website linked to their Myspace page. “We had forgotten we even had a Myspace page,” he says.

Irvin has known Boroughs for about 20 years and says her undercover work was perfectly in character. “It’s a testament to who she is,” he says. “She’s a tenacious one, so it didn’t surprise me at all that she was able to nab it.”