In this "Doctor Who" serial, the Doctor (Tom Baker), Romana (Lalla Ward) and robotic dog K-9 (voice of David Brierly) are forced to materialize on the planet Chloris, whose fierce ruler stokes local fears by keeping a strange creature as a pet inside an old mining pit. The plot thickens when a band of scavengers in search of priceless metal seizes Romana and starts sizing up K-9, and the Doctor jumps into the pit to investigate.