38. Robots Of Death 14.17-14.20
The serial itself is in an interesting discussion of attitudes surrounding the advancement of robot technology particularly with regard to attempts to replicate humanness. It is also notable for particularly physical murders, victims are choked and some of the deaths were even bloody. It is also the only serial on this list to feature companion Leela, a huntress from a future humankind civilisation where humanity is far more integrated with natural world. However, it is most notable for the Doctor's effort to explain transdimensional engineering or why the TARDIS is bigger on the inside to Leela via a pair of boxes. It does not seem to help Leela much, but it is a clever demonstration, and nice compared to the general spouting of the phrase that has occurred so often since the start of TARDIS trips.
37. Hand Of Fear 14.5-14.8
This particular adventure marks a truly horrible time for companion Sarah Jane who is: knocked unconscious by an explosion, possessed by an alien entity, knocked unconscious by the Doctor, hypnotised, and nearly obliterated twice in a nuclear reactor, walked through a mass grave where she nearly fell into an abyss, and half froze in the caves of an alien planet, all leading up to Sarah Jane's truly heartbreaking departure as a companion where the Doctor sort of dismissively throws her out. Other interesting notes include this story featuring a quarry as a quarry, a nod to the production of many alien worlds requiring quarries to bring them to life, and fans of Modern Who will recognise the drastic solution of the Kastrians as vaguely familiar to Last Great Time War. A truly lose-lose day all the way round for everyone.