S4 E1: Hitler's Secret Weapon

S4 E2: The Hot Blooded Dinosaurs

S4 E3: What Price Coal?

S4 E4: The Sunspot Mystery

S4 E5: The Plastic Prison

S4 E6: Incident at Brown's Ferry

S4 E7: Bye Bye Blackbird

S4 E8: The Pill for the People

S4 E9: The Gene Engineers

S4 E10: The Human Animal

S4 E11: The Wolf Equation

S4 E12: The Dawn of the Solar Age

S4 E13: The Business of Extinction

S4 E14: The Red Planet

S4 E15: Tongues of Men (1)

S4 E16: Tongues of Men (2)

S4 E17: Linus Pauling: Crusading Scientist

S4 E18: Across the Silent Barrier

S4 E19: The New Healers