TV Guide National Geographic Channel Tuesday

Phoenix is under the control of Mexico's powerful, ruthless Sinaloa Cartel; the head of the sheriff's dedicated drug task force talks.

As New York City counts down to New Year's Eve, drug gangs shift into high gear in order to meet the extraordinary demand for their products.

Nashville's musicians often turn to selling drugs; a meth user covers his costs by cooking and selling it; a task force cleans up after meth cooks.

A North Philadelphia addict sells clean needles; an HIV-positive user tests heroin for wholesalers; a ridealong with two Philly cops.

Progressive Portland, Ore., has become a haven for the homeless, and many of them choose drug dealing as an occupation; the police go undercover to stop them.

The number of users of the extra-pure, extra-strong variety of MDMA known as "molly" is skyrocketing as electronic dance music grows in popularity.

Host Bear Grylls examines jungle habitats, in which only the fittest creatures survive, and jaguars, orangutans and other animal species are featured.

After the spring snowmelt, the next generation races to finish vital hunting, trapping and building projects before the Arctic winter returns.

The next generation confronts spring in Alaska and every minute counts to reap its rich rewards.

Unfamiliar territory forces the hard-nosed Alaskan residents to lean on friends and family as they prepare to embrace another harsh winter season.

As the Arctic winter looms, Alaska's toughest inhabitants must finish building projects and hunt big game before the temperatures dive below zero.

The next generation must be ready for the dangers and challenges that can arise living in the wild backcountry of Alaska.

With winter on the horizon, the next generation must adapt and learn the lessons of Alaska's harsh backcountry to survive another day.

Will heads to the South Pole, where temperatures can drop below minus 100 degrees Fahrenheit; he skis and treks across giant icefields.

Will ventures deep into the Ecuadorian Amazon on an expedition in search of deadly creatures; they abseil 200 feet into a cave network.

Will, Bryan and Carla join local Waorani elder Penti Baihua in the Amazon, in search of the world's biggest snake: the giant green anaconda.

Guided by happiness expert professor Dacher Keltner and local writer Tshering Denkar, Will Smith treks to one of the highest villages in the Himalayas.

Will travels to the South Pacific on an expedition to a remote island threatened by rising seas. An exploration into an incredible marine paradise.

Will travels deep into the Kalahari Desert to meet the San people, one of the oldest hunter-gatherer groups on Earth. He must join them on a hunt.

Will joins an expedition to dive under the ice at the North Pole to help polar ecologist Allison Fong capture world-first scientific samples.

Will travels to the South Pacific on an expedition to a remote island threatened by rising seas. An exploration into an incredible marine paradise.

Will travels deep into the Kalahari Desert to meet the San people, one of the oldest hunter-gatherer groups on Earth. He must join them on a hunt.

Will joins an expedition to dive under the ice at the North Pole to help polar ecologist Allison Fong capture world-first scientific samples.

Margot, Matty, Billy and Emile and Gilbert negotiate some early, pre-winter challenges as they begin work on their new Northern homesteads.

Margot, Matty, Billy and Emilie and Gilbert step up their efforts to finish their homesteading projects before the harsh, Canadian winter sets in.

The harsh, northern winter has arrived, forcing young Canadians to take on a whole new set of icy, backwoods challenges.

The NWS homesteaders face off against the harsh and unforgiving northern winter as they battle to survive and thrive in the vast Canadian wilderness.

Locked in the depths of a harsh and unforgiving Canadian winter, the NWS homesteaders look to the land to help them replenish much-needed resources.

This is a planet on the move, animals in every landscape are embarking on epic migrations in search of food, shelter and love.