The Menagerie by Martin Day

The Menagerie features the second Doctor and his companions Jamie and Zoe on a rain soaked backwater of a city on a primitive planet.

The ruling Knights of Kuabris are trying to keep order as hideous creatures are emerging from sewers to attack the inhabitants. Jamie is captured and while he languishes in a damp, dark castle dungeon, the Doctor must lead an expedition beneath the city to look for the legendary Menagerie of Ukkazaal.

Things are worse for Zoe however as she is sold as a slave to a traveling freak show...