This season aired between 3rd September 1977 to 11th March 1978. It featured The 4th Doctor with Leela and K9. The main enemies/aliens are The Rutans, The Swarm, The Fendahl, Gatherer Hade, The Collector, Minyans, Sontarans and The Time Lords. The episodes are:
95. The Sun Makers
96. Underworld