Doctor Who: The Creature from the Pit (1979)

Another adventure for everyone's favourite Time Lord. When the Doctor (Tom Baker) and Romana (Lalla Ward) land on Chloris, a planet suffering from a lack of metal and an over-abundance of lush plant life, they become caught up in a dangerous power struggle. The planet's last metal mine is controlled by Lady Adrasta (Myra Frances), and she is determined to increase her control by using the Doctor's scientific knowledge; but rebel bandits are gathering outside the gates, waiting for the chance to end her regime.