(CNN) -

It's 8 p.m. in Chelsea, Massachusetts, just across the Mystic River from Boston. For Lt. Detective David Betz, his day is about to get busy.

After about 30 minutes, Betz, head of the Narcotics and Vice Division of the Chelsea Police Department, leaves to meet with a confidential informant who has been assisting with a case.

"When we make contact with this person, hopefully they will be able to make a call to any number of their sources, and we'll try to buy some heroin off the street tonight. ... This is basically the meat and potatoes of what we do," Betz says.

Chelsea is in the middle of a heroin epidemic. In March, Gov. Deval Patrick declared a public health emergency in Massachusetts in response to the growing opioid addiction sweeping the entire state. From 2000 to 2012, the number of unintentional opiate overdoses in Massachusetts increased by 90%, he said.

According to the Drug Enforcement Administration, it's happening all across America. The demand for heroin is reaching unprecedented proportions -- fueled in part by a growing number of people who get hooked on prescription painkillers and soon need a cheaper way to get high.

Like heroin, the painkillers morphine, methadone, hydrocodone and oxycodone are all opioids and have a similar effect on the nervous system.

Heroin, however, is cheaper to get and easier to find.

In Chelsea, according to Betz, the majority of illegal prescription pill sales take place behind closed doors, but a heroin deal can be made in the heart of downtown Chelsea, at a busy part of town called Bellingham Square. Betz says in Chelsea, one small dose of heroin runs $10 to $40 depending on size and quality. Prescription opioids, on the other hand, sell for $1 per milligram, or $80 for one 80mg pill.

After waiting for the informant to meet with an alleged dealer and make the buy, Betz and several other detectives take the informant into custody. They search the informant to make sure there is no pocketed heroin or cash, and have the person hand over the drugs. The informant has bought five small bags of heroin. Betz and his team will use the information to build a case against the dealers and secure search warrants and arrest warrants. Informants often work with police to get their own charges reduced.

"For every 10 people we arrest, there's probably 15 or 20 people that are waiting to take over because of the money they could make. It's such a lucrative business, you know. Why would you want to deliver pizza for $8 an hour when you can make $800?"

But Betz says Chelsea is not so different from any other town when it comes to drugs. "The smallest community in the heartland of America is going to have some type of drug problem," he says. "I mean drugs are, you hate to say, they're as American as apple pie."

Betz describes an artery-like network of distribution and delivery that ensures a steady flow of heroin, prescription narcotics, and other drugs into the country -- eventually working its way into small cities and towns like Chelsea.

From Southeast Asia or Mexico, the drugs make it into the United States, Betz says. The drugs are smuggled into New York, then Connecticut and Rhode Island before heading into Massachusetts and the Boston area. From there, it is a short trip across the Tobin Bridge to Chelsea. Betz says small cities often have a tougher battle against drugs than bigger cities because of lower income and resources.

"The more affluent a community, sometimes they're able to keep their problems more under wraps than a city that has somewhat less of population who is well off. It's supply and demand, and if the buyers weren't here, the dealers would have to look elsewhere to sell. It's a double-edged sword. If the dealers weren't here, the buyers wouldn't come around."

What's more, much of the drug problem in Chelsea doesn't come from inside Chelsea, Betz says. He estimates 50% of the city's heroin buyers and dealers come from the bordering cities of Everett, Revere, Winthrop and, of course, Boston.

"When they're arrested, they'll give us their information -- where they are from, where they were born, and just being familiar with the area, we know certain communities are a lot more affluent then say, Chelsea. They come here, and we'll ask them how did you end up here from a suburb of million-dollar homes, and they'll say they got hooked on opiates, they ran out of money, they're not available there like they are here," says Betz, "The easiest way to look at it is, drugs have no borders."

With a department of around 100, Betz and his vice squad try to fight heroin in a city of about 35,080 crammed into 1.8 square miles on the edge of Boston. He is proud of his team's work and believes they make a difference, but he doesn't lose sight of what they're up against.

"I think that drugs as a whole are one of the major problems that are plaguing our society, and aside from all the public intervention that we try to do, the people themselves have to have the will and the desire to want to get past it themselves. If they don't, there's no public service programs or no magic pill to better the problem."

Betz and team have had a relatively successful night making a controlled buy with their informant and gaining information to build a case against suspected heroin dealers. Still, Betz knows that each day is a new day, where the effort to end the heroin problem in Chelsea continues.

"You're trying to keep them from selling the drugs but it's really almost temporary," he says, "You're constantly pushing back the ocean, basically."