The Zarbi

The narrative opens with Ian recovering from an unknown attack, his face blistered, as the Doctor attends to him. They quickly discover the TARDIS has vanished, leaving them stranded on a desolate, alien world. As they navigate the harsh terrain, they shed their protective coats, adapting to the planet's atmosphere. Their search for the ship and their missing companion, Barbara, yields unsettling clues: peculiar tracks, then distinct claw marks, and finally, a hollow, chrysalis-like object. The Doctor identifies these findings as indicators of Vortis, a planet in the distant Isop galaxy, a revelation that deepens the mystery of their forced landing. Simultaneously, Barbara, separated from her companions, falls victim to a winged Menoptra, who guides her into a hidden cave. There, another Menoptra removes and destroys her gold bracelet, a seemingly innocuous action whose significance remains unknown to Barbara. She awakens to find herself a prisoner, unaware of the larger conflict brewing around her. Meanwhile, inside the hijacked TARDIS, Vicki struggles to maintain her balance as the ship is violently dragged through unseen tunnels. A giant ant-like creature's head fills the scanner, confirming the ship's capture by hostile, unknown entities. This act establishes the immediate peril for all three companions, introduces the planet Vortis and its indigenous life, and sets the stage for the unfolding conflict.

Barbara, now a captive within the Menoptra cave, learns of the fierce, ongoing war between her captors and the insectile Zarbi. The Menoptra, specifically Hrhoonda and Vrestin, engage in a heated debate over Barbara's fate, with some advocating for her execution as a potential liability, while others see her as a possible ally against the Zarbi. Seizing an opportunity amidst their disagreement, Barbara attempts a desperate escape, knocking over Hrostar, only to be recaptured by the Zarbi outside the cave. Concurrently, the Doctor and Ian, continuing their search for the TARDIS and Barbara, find themselves surrounded by a swarm of Zarbi and their smaller, woodlice-like companions. The creatures compel them forward with an undeniable, silent authority, forcing them to obey. Their journey leads them to a colossal structure of organic matter, where they witness its strange, continuous growth. Inside this structure, Vicki, having ventured out of the now-stationary TARDIS, confronts the Zarbi in what appears to be their control room. The Doctor and Ian soon arrive, reuniting with Vicki, but their relief is short-lived as Barbara remains missing, her fate unknown to them. The Doctor attempts to communicate with the Zarbi, but their intentions remain opaque, deepening the mystery and the sense of impending danger. This act intensifies the individual predicaments of the companions, reveals the power of the Zarbi, and brings the main group back together, albeit without Barbara, setting up a new phase of the conflict.

Within the besieged Menoptra cave, Vrestin and Hrostar desperately attempt to establish contact with their Menoptra invasion forces, hoping to warn them of the Zarbi's overwhelming power and the threat of the Animus. Their efforts prove futile; the cave's natural defenses block their signals, and the broader Menoptra forces maintain radio silence to avoid detection. Just as they consider a perilous attempt to transmit from outside, the Zarbi launch a brutal assault. Barbara, now under the mind-controlling influence of a wishbone-shaped device, leads the Zarbi directly to the Menoptra's hidden sanctuary. Hrhoonda bravely attempts to repel the invaders with a crystal spear but falls victim to a larvae grub's attack. As the cave is breached, Vrestin manages to escape through a hidden passage, leaving Hrostar to face the onslaught. Hrostar swiftly removes the mind-control device from Barbara, breaking the Zarbi's hold. Barbara, disoriented, realizes the gold bracelet she wore earlier, and now this device, are instruments of Zarbi control. Her brief moment of clarity is cut short as the Zarbi capture both her and Hrostar, condemning them to forced labor in the dreaded Crater of Needles. This act culminates in a direct confrontation, reveals the Zarbi's method of control, and leaves Barbara and Hrostar in a dire new predicament, while the Doctor, Ian, and Vicki are left in the Zarbi control room, unaware of their companion's capture and new destination.