The Doctor's unresolved philosophical conflict as he veers between detached amusement at forcing evolutionary truths on terrified Deciders, and compassionate urgency to save lives through unconventional methods.

The Doctor works urgently in the confined Science Unit, analyzing genetic fragments of the alien marsh creatures and their victims while his companions assist. Adric identifies the raw biological components …

Romana and Keara press the Doctor about the marsh creatures' origins while he identifies Dexeter and spider remnants in their cells, confirming an unbroken lineage with the Deciders. The revelation …