Deadly Ascent A team of doctors and climbers on Denali test the body's response to extreme cold.
Deadly Shadow of Vesuvius The shattered remnants of the Roman city of Pompeii bear witness to the risk that the people of Naples still face today.
Death Star Astronomers investigate gamma-ray bursts, the most powerful celestial explosions since the big bang.
Decoding Nazi Secrets Allied technologies developed at Britain's Station X helped halt the onslaught of the Third Reich and set the stage for today's computers.
Deep Sea Invasion A toxic aquarium plant is accidentally released into the Mediterranean, overwhelming marine life and threatening to spread worldwide.
Descent Into the Ice A team of "glacionauts" ventures into a labyrinth of unexplored and hazardous glacier caves on France's Mt. Blanc.
Diamond Deception Makeshift labs in China and Russia are turning out synthetic gemstones that rival natural diamonds.
Dimming the Sun New evidence that air pollution has masked the full impact of global warming suggests the world may soon face a heightened climate crisis.
Dirty Bomb Radiation experts play out a frightening terrorist scenario—exploding a bomb laden with radioactive materials.
Doctors' Diaries Seven doctors, 21 years... Saving lives is only part of the story.
Dogs and More Dogs How and why did man's best friend evolve from wolves, and why are dogs so remarkably diverse today?
Dying to Be Thin Life-threatening eating disorders such as anorexia and bulimia are on the rise among America's youth.