Season 4

1.Hitler's Secret Weapon

2.The Hot Blooded Dinosaurs

3.What Price Coal?

4.The Sunspot Mystery

5.The Plastic Prison

6.Incident at Brown's Ferry

7.Bye Bye Blackbird

8.The Pill for the People

9.The Gene Engineers

10.The Human Animal

11.The Wolf Equation

12.The Dawn of the Solar Age

13.The Business of Extinction

14.The Red Planet

15.Tongues of Men (1)

16.Tongues of Men (2)

17.Linus Pauling: Crusading Scientist

18.Across the Silent Barrier

19.The New Healers