Doctor Who The Keys of Marinus by Philip Hinchcliffe

This narrative follows the Doctor, Susan, Ian, and Barbara as they arrive on the planet Marinus, a world featuring a glass beach and a sea of acid. To reclaim their ship, they are coerced by the Keeper Arbitan to recover four micro-circuits hidden across the globe to power a machine of absolute justice. Their journey leads them through a series of treacherous environments, including a city ruled by telepathic brains, a sentient jungle, and a frozen wasteland. Along the way, they must outwit the invading Voord, a ruthless race seeking to use the machine for totalitarian control. After exonerating Ian from a wrongful murder charge in a futuristic court, the group returns to find Arbitan dead and the machine rigged to explode. The story concludes with the destruction of the machine and the travelers' narrow escape back into the TARDIS.