Holly invites Cha-Ka to test-ride their newly built outrigger-balanced canoe, but the Paku would rather stay along the shore. When Holly calls Cha-Ka a "chicken", he rebuts her taunt by pointing out that no one that went down the river has ever returned (who is he talking about?). Will arrives to add that it could mean that the river is the way out of the Land. (He seems to have forgotten that the family tried exploring the river early in the 1st season [Downstream], only to find that it is circular; the Land of the Lost is a small, closed universe, with the time doorways as the only way in or out.) Will pulls a worm from a pouch, suggesting that they fish for their lunch while they explore the river, but Cha-Ka snatches it from Will's hand, thinking that the worm are their lunch. Will asks Holly to load their gear on the canoe while he and Cha-Ka head out to cut some fishing poles and fetch Uncle Jack. He advises his Pakuni friend not to toss the entire pole in the water if he gets a bite (which could explain why Will seems to be content with quickly slopping together a makeshift pole in half an hour, in contrast to when he laboriously crafted one with a working reel [A Nice Day]). Meanwhile, downstream, a woman dressed in a toga unclogs debris blocking a stream when a large praying mantis crawls on her foot; the offended woman, wearing a sloppy coat of dark green makeup on her face and rubber snakes in her hair, turns the pesky insect to stone.

While cutting some bamboo for fishing poles, Cha-Ka believes that he has discovered the pleasure of fishing: eating the pole while feeding the worms to the fish. Will tries to set him straight by emphasizing that the fish are to be eaten, not the pole or worms, but Cha-Ka remains puzzled. Just then Holly calls out for help, prompting Will and Cha-Ka to rush to her aid. The boys arrive at the shoreline, but Holly and the boat are gone; Cha-Ka deduces that she must have gone downstream. Will decides to first get Jack; meanwhile, Holly cries for help, sitting on the cross-braced bamboo poles connecting the outrigging to the canoe (she can't sit in it since the cheap prop is way too small). The Medusa, in her human form, throws out a rope to save poor Holly; Miss Marshall catches the rope and gets towed in to shore. The lady politely advises that her rescued friend be more careful when using King Neptune's waters. After Holly introduces herself, she asks her rescuer her name; Medusa pauses briefly, then replies that her guest can call her "Meddy". Though Holly is very grateful for being rescued, she feels she should start on the long way back. Meddy quickly attempts to persuade Holly not to leave; she insists that her guest stay put with her until her family comes to find her, since nightfall is not far off and the jungle is too dangerous for a young girl to travel alone. Before her Holly can reply, Meddy takes her guest's hand and leads the way to her home; they leave the canoe along the shore as a sign for Holly's family.

Will and Cha-Ka return to the Temple, relating Holly's call for help and disappearance. They all head downstream, having to pass the swamp along the way, where they end up encountering LuLu. They get by the water-hydra by each running in a separate direction; LuLu gets confused enough for all to pass by. Back by Meddy's home, she shows Holly her Garden of Eternity; the setting and background music cheaply hint at the surreal mood found in many original Star Trek episodes. Uncle Jack finds the washed-out dam, apparently concluding that it was the cause of the strong current that swept away the canoe with Holly. Cha-Ka discovers a trail, with fresh tracks from Holly and one other person; they hurry on tracking their kin, worrying about what may have happened.

As the women stroll through the garden's miniature gothic pillars, Meddy warns Holly not to wander from the path; when Holly asks why, Meddy tosses out a stick, whereupon the vines along the walls creep over to strangle it. Meddy leaves her guest to gaze in awe and fear at the vines while she goes over to freshen up at her vanity table. She talks to her sentient reflection within her magic mirror, conveying her delight in luring Holly and soon her family to her garden to become permanent residents. She proposes a toast with her reflection, but is interrupted by another call of help from Holly. A triceratops just outside the garden threatens Holly; she tosses a stick at it, but the beast just chomps it. Meddy commands Holly to flee, and turns into Medusa once Holly is out of sight. The dinosaur turns to stone, Medusa posing all the while with arms crossed and white teeth bared.

Will, Jack and Cha-Ka arrive at the edge of the Garden of Eternity, stumbling upon what appears to be an outstandingly crafted statue. When Will wonders who could have made it, Cha-Ka voices his belief that the Great Pakuni in the Sky put it there. Uncle Jack is quite impressed by the unbelievably perfect statue; he and Will plan to return to it for further study once Holly is found. Deeper in the garden, Holly envies Meddy's clothes and perfume; when asked where she got her wardrobe, Meddy simply answers that she has "very special talents". While Holly is busy examining the robes, Meddy's reflection scolds her for taking the risk of getting caught when she turned the triceratops to stone. Her reflection advises that Meddy let Holly wear her pink robe, and after a bit of arguing, her reflection succeeds in persuading her real self. When Meddy suggests that her guest try it on, Holly excitedly dons the garment; it looks just like a bathrobe, which she puts on right over her own clothes. Meddy then tells Holly to "go out and play like a good girl" (c'mon, Holly must be at least 16). Holly's host resumes arguing with her mirror, causing her offended reflection to disappear.

Holly strolls around to discover the petrified triceratops; horrified, she also finds a statue of a civil war soldier with a cannon. Meddy startles her guest while she reached out to touch the statue, politely reminding her that she should not stray from the path. Though the soldier and his cannon look nothing like Mr. Collie [Downstream], Holly claims that it reminds her of a soldier she once met. Miss Marshall goes on to question her host about the fate of the triceratops that bothered her earlier; Meddy vaguely replies that it will no longer be bothering them, and sweetly advises her worried guest not to ask so many questions. Holly removes the robe, insisting that she really must be going; just then Cha-Ka points out Holly and the woman to his companions Will and Jack. Before the men and Cha-Ka can move ahead to meet up with their kin, the creeping vines quickly bind them, stopping them in their tracks. Meddy coaxes a reluctant Holly to stay put for now, proposing that her soon-to-arrive family will enjoy spending time in her garden. Jack, Will and Cha-Ka continue battling the vines; Will even bites at the one strangling him.

Once the men finally cut themselves free with their knives, Cha-Ka insists on scouting ahead alone since he is small and possesses the best skills. Meddy leaves Holly alone for the moment, making an excuse about getting a present for her to take home in order to get a chance to talk to her magic mirror. While Meddy argues with her reflection about wanting to keep her guest alive as bait for the other family members, Cha-Ka makes contact with Holly. After the Paku explains that Jack and Will wait further back, Holly tells him to report that she believes Meddy can turn things to stone. Meddy continues to disagree with her mirror on when to turn Holly to stone; when she tells her reflection to bud out, she becomes distraught when it disappears once more.

Once Cha-Ka relays the information to the men, Uncle Jack realizes that "Meddy" is a medusa. The Paku conveniently asks Jack to define the term, whereupon he and Will elaborate on the Greek legend for those unfamiliar with it in the audience. After Jack verifies with Cha-Ka that he witnessed Meddy talking to her mirror, Jack announces that he has a plan to trap their foe. Will doesn't understand why they can't just get Holly and run, but Jack points out the risk that she will come after them later to turn them to stone. Jack volunteers to act as bait while Will and Cha-Ka rescue Holly (his plan never included "trapping" Meddy, instead simply sounding like Will's proposal); Cha-Ka understands the concept, likening it to the worms they used for fishing. Uncle Jack warns them not to look in the Medusa's direction once she has changed form, and advises that they pass on the warning to Holly, too.

Meddy pleads to her mirror for her reflection to return, worrying that she may never again have the chance to admire herself vainly. Once her reflection reappears, she scolds it quite harshly, but it commands her to promptly take care of Holly. Will and Cha-Ka are caught warning Holly about Medusa; Meddy sweetly thanks Holly for "inviting" her family to her garden, but ponders the whereabouts of Uncle Jack. She calls upon her creeping vines, whereupon they tie the garden gate shut; meanwhile, Uncle Jack sneaks around from behind to steal the mirror from the vanity. Jack knocks over a crystal vail while removing the large mirror from the table; it shatters on the pavement, clueing Meddy in on his arrival, so she leaves the others to find him. Jack manages to get out of sight for now; Will effortlessly cuts the motionless vines from the gate and directs the group to escape. When Meddy discovers that both her mirror has been stolen and the Marshalls kids have escaped, she becomes angry, turning into the Medusa, and punishes the vines on the gate with petrifaction. Reverting back to human form, Meddy tiptoes around her garden, making sweet but unconvincing attempts to lure the Marshalls out into the open. She begins to offer to make a truce in return for her mirror, but Uncle Jack makes a noise while sneaking from one pillar to the other behind her. Uncle Jack doesn't quite fit crouching behind the pillar, so Meddy turns into the Medusa and politely asks Jack to come out and greet her. Uncle Jack jumps out, holding the mirror in front of his face; he succeeds in tricking Medusa, turning her to stone. Her sentient reflection in the mirror (which shouldn't be there if her monster-reflection was present) bad-mouths her just before the mirror shatters. Before Jack leaves, he takes a moment to gaze in awe at the petrified Medusa; the others come out of hiding to do the same.

On their way back to the Temple, the Marshalls stop to comment on their adventure. Jack explains that he got the idea to use the mirror from the Greek hero of legend, who exploited Medusa's harmless reflection to guide his sword in slaying the monster. (Uncle Jack's logic is completely flawed; if a medusa's reflection is harmless, why did it turn her to stone?) Will pities Medusa's last moment when she realized she would be turned into an ugly statue; Holly adds comments on the consequences of vanity and anger.