The Doctor and Jo arrive in 1926 on the cargo ship SS Bernice. But when the TARDIS is taken by a huge hand and a dinosaur appears, the Doctor suspects that all is not as it seems.
The Doctor and Jo have been miniaturised and trapped inside a Miniscope, the property of showman Vorg. The Scope has been impounded on the planet Inter Minor and may be destroyed.
The Drashigs are pursuing Jo and the Doctor through the Miniscope. On Inter Minor, scheming bureaucrats intend to release the Drashigs in a plan to topple their leader.
The Doctor is desperate to save the lives of Jo and everyone trapped inside the Miniscope, but is hindered by the Inter Minorans who have their own agenda.