Five Hundred Eyes

The episode opens with Marco Polo's caravan in a state of utter desperation, stranded in a vast desert, their water supplies completely depleted. Polo's narration reflects a profound sense of hopelessness, fearing their imminent end. Ian and Barbara share his grim outlook, their concern amplified by the absence of Tegana, who was meant to meet them with water. Within the TARDIS, a miraculous discovery unfolds as the Doctor wakes to the sound of dripping water – condensation forming on the ship's interior due to the extreme temperature differential. He urgently rouses Susan, and they meticulously collect every precious drop. This unexpected reprieve initially leads to conflict when Polo, distrustful and incredulous, accuses the Doctor of lying about having water. Ian and Susan patiently explain the scientific phenomenon of condensation, eventually convincing Polo, who cautiously samples the water. The caravan then reaches an oasis, where they finally reunite with Tegana. He offers a plausible, though ultimately false, account of being delayed by bandits heading towards Karakorum. Polo, relieved by their survival, credits the Doctor's discovery. However, Barbara immediately senses inconsistencies in Tegana's story, particularly noting the absence of any signs of a bandit campfire despite the cold night. Her suspicions grow, and she voices her concerns to Ian, suggesting Tegana fabricated the bandit encounter to justify his delay. Polo, prioritizing their journey to Tun-Huang, dismisses Barbara's misgivings and, out of continued distrust, confiscates the TARDIS key from the Doctor, further asserting his authority and control over the group's movements. This act establishes the immediate crisis, the Doctor's unique (if accidental) solution, and the first seeds of treachery sown by Tegana, setting a tense tone for the journey ahead.

The caravan arrives at Tun-Huang, a city renowned for its temples, marking a significant milestone in their journey. Polo introduces the ominous Cave of Five Hundred Eyes, a place steeped in the dark history of the Hashashins, a sect known for their drug-induced assassinations. This exposition immediately establishes a sense of foreboding and introduces a key location for the unfolding drama. Meanwhile, the Doctor, ever resourceful, reveals to Ian that he anticipated Polo's restrictions and secretly crafted a duplicate TARDIS key during their time at the oasis, a testament to his cunning and determination to repair his ship. This moment of cleverness provides a brief, lighter interlude before the narrative darkens. Ping-Cho then captivates the group with a vivid tale of Ala-eddin, the Old Man of the Mountains, and his Hashashins, describing their method of luring followers into a false paradise with hashish before dispatching them as ruthless assassins. This narrative serves as a powerful thematic echo, foreshadowing the deception and betrayal that will soon be unveiled. Barbara, her suspicions about Tegana intensifying, discreetly follows him as he leaves the gathering. Her covert pursuit leads her directly to the fabled Cave of Five Hundred Eyes, where she secretly observes Tegana meeting with Acomat and Malik. She overhears their treacherous plot: Tegana, a Mongol warlord, is collaborating with Noghai to ambush Polo's caravan en route to Shang-Tu, seize the TARDIS—which they covet as a "caravan that flies" for Noghai's army—and ruthlessly eliminate Polo and all his companions. The chilling revelation of this deep-seated betrayal, combined with Barbara's perilous eavesdropping, culminates in her discovery by a Mongol guard, leaving her in grave danger and marking a critical turning point in the episode.

News of Barbara's disappearance plunges the Tun-Huang way station into chaos and panic. Polo, furious and deeply concerned, immediately organizes a search party, dividing the city into sectors for Ian and Tegana to cover, while explicitly ordering the Doctor and the others to remain behind. His directive underscores his continued attempts to maintain control and protect the group, though his methods are often at odds with the Doctor's independent nature. Despite Polo's strict instructions, the Doctor, driven by his concern for Barbara and his inherent defiance of authority, prepares to venture out on his own. Susan and Ping-Cho, having pieced together Barbara's interest in the Cave of Five Hundred Eyes, approach the Doctor with their theory, offering a crucial lead. A local spy named Chenchu, who has been observing the Doctor, is then pressed for information. Under the Doctor's insistent questioning, Chenchu reluctantly reveals the precise location of the haunted Cave of Five Hundred Eyes, warning of its dangers and the spirits of the Hashashins said to roam within. Undeterred by the ominous warnings and Polo's orders, the Doctor resolves to go. Susan and Ping-Cho, demonstrating their unwavering loyalty and courage, insist on accompanying him, forming an unlikely search party. As they enter the eerie Cave of Five Hundred Eyes, the Doctor, with characteristic scientific curiosity, momentarily becomes engrossed in the cave's geological formations, marveling at the quartz and mineral veins, a brief intellectual detour amidst their urgent mission. Susan, however, quickly refocuses him on their primary objective: finding Barbara. The act culminates with Chenchu, the spy, reporting the Doctor's unauthorized expedition to a furious Tegana, who now realizes his treacherous plans are in jeopardy, raising the stakes significantly for the Doctor and his companions as they delve deeper into danger.