The mandrels’ existential battle as sentient beings, first controlled by CET projection then liberated by The Doctor’s acoustic counter-signal

Stott's group has been driven back by the mandrels' aggressive advance when the Doctor arrives. With Romana at his side, he surprises everyone by pulling out a simple dog whistle. …

With a pocket dog whistle in hand, the Doctor herds the hostile mandrels back into the Eden projection's boundary, shooing them through with practiced ease. His casual confidence belies the …

The Doctor examines Della’s recovery before turning to the crisis at hand—the Eden crystal and the smuggled Vraxoin creatures inside. Romana locates Tryst’s smuggled menagerie and proposes using the TARDIS …