S31 E1: Infinite Secrets

S31 E2: Who Killed the Red Baron?

S31 E3: The Elegant Universe: Einstein's Dream (1)

S31 E4: The Elegant Universe: String's the Thing (2)

S31 E5: The Elegant Universe: Welcome to the 11th Dimension (3)

S31 E6: Wright Brothers' Flying Machine

S31 E7: Magnetic Storm

S31 E8: Volcano Above the Clouds

S31 E9: MARS Dead or Alive

S31 E10: Secrets of the Crocodile Caves

S31 E11: Dogs and More Dogs

S31 E12: Descent Into the Ice

S31 E13: Crash of Flight 111

S31 E14: Life and Death in the War Zone

S31 E15: Hunt for the Supertwister

S31 E16: World in the Balance: The People Paradox (1)

S31 E17: World in the Balance: China Revs Up (2)

S31 E18: Battle Plan Under Fire