“Explorer” (9 p.m., National Geographic) correspondent Lisa Ling goes “Inside North Korea” for a hidden-camera glance at the world’s most secretive dictatorship. Known as the “hermit kingdom,” North Korea has done a remarkable and creepy job of keeping the rest of the world at bay.

A land where cell phones and the Internet are forbidden, Korea boasts one of the world’s largest armies and a border bristling with land mines and barbed-wire fences. And these are not to prevent an invasion from South Korea but to keep its starving population from defecting.

Ling joined Dr. Sanduk Ruit, an eye surgeon from Nepal who had volunteered to perform more than 1,000 cataract surgeries in North Korea. Using hidden cameras and footage shot while under the constant scrutiny of North Korean minders, Ling showcases life under Kim Jong Il, one of the world’s most absolute dictators.

The History Channel follows up on its two-hour romp through the Dark Ages with a weeklong look at the barbarians who defined the era. Tonight’s rampaging hordes includes “The Vandals” (8 p.m., History).

Hope springs eternal, and spring training brings hope to every baseball fan – particularly Chicago Cubs fans, who have not cheered a World Series champion since 1906. “Real Sports with Bryant Gumbel” (10 p.m., HBO) sits down with Lou Pinella, the new manager of the Cubs, as he discusses his chances for ending this century-long drought.

Other highlights

Michael wants to confront the president on “Prison Break” (8 p.m., Fox).

Chris’ class presidency unravels on “Everybody Hates Chris” (8 p.m., CW).

Yonk suffers a heart attack on the season finale of “The Class” (8:30 p.m., CBS). “Class” dismissed.

Frightening visions of tomorrow on “Heroes” (9 p.m., NBC).

As the White House reels, Logan schemes on “24” (9 p.m., Fox).

After a supporter of an eminent-domain seizure is slain, a whole neighborhood falls under suspicion on “CSI: Miami” (10 p.m., CBS).

With Sean in the hospital, Tommy takes action on “The Black Donnellys” (10 p.m., NBC).

Laura gets bad vibes from Brian and Bridget on “What About Brian” (10 p.m., ABC).