Holly and Cha-Ka are heading back to the Temple with firewood when they hear the thunder of a strong storm approaching. Torchy comes along, forcing them to flee; Cha-Ka drops his armload of wood. After reaching a safe distance, the two encounter a colorful flying bug; Cha-Ka suggests that they capture it. Holly insists that they follow Uncle Jack's orders to gather as much firewood as possible in preparation for the storm, but the Paku is defiant, informing Holly that he will catch the bug and return to the Temple later. Holly begins to lecture Cha-Ka on how "this is no time for play", but she sees that it will do no good, so she rushes back to the Temple, leaving the Paku behind. Cha-Ka's first attempt to seize the giant golden beetle fails; as it flies away, he calls out to it, promising not to do it any harm. The insect escapes by flying over to a log at the swamp's edge, where it lands to munch on a yellow chrysanthemum. LuLu surfaces to defend her territory, but Cha-Ka manages to catch the humongous, motionless insect in time. He rushes off with his prey, barely escaping from the swamp hydra.

Back at the Temple, Jack and Will return with firewood; Jack asks Holly where Cha-Ka is. Holly reports that he is inside playing with a bug, prompting Will to comment that the Paku should be pitching in with the chores. Will volunteers to talk with Cha-Ka, but Jack feels he should be the one to give the "being a member of the family" speech. They all head inside, where Cha-Ka shows off his prized catch; mesmerized by its many colors, he decides to keep the insect. Uncle Jack informs the Paku that work must be done, but Cha-Ka rudely replies that he just did work the day before. Jack crouches down and gently gives the Paku a lecture on the importance of serving the needs of the family first; Cha-Ka understands, and volunteers to help get firewood. When Cha-Ka reaches over to put the beetle in a wooden cage, Holly scolds the Paku for wanting to imprison the little creature. Against Holly's advice, Cha-Ka insists on caging the bug, claiming that he will treat the insect well, but when he tries to stick it into the cage, the beetle bites him and flies away. Jack calls for the whole family to head out to gather firewood, but Cha-Ka, agonizing over the insect bite, promises to follow behind in a moment. Once the Marshalls have left the compound, Cha-Ka immediately stops his feigned agony. With a demonic look upon his face, he picks up a hunting knife and begins to trash the family's belongings. After overturning the table, toppling the shelf, and throwing various items, the mad Paku runs off wielding the knife.

Out in the jungle, Cha-Ka stops to spy on the Marshalls gathering wood. Grumpy prowls the area nearby, so Cha-Ka gets the tyrannosaur's attention. The Paku manages to provoke Grumpy into chasing him, where he runs back toward the family and then escapes into the foliage. The Marshalls are caught off guard by the charging beast, and when they flee, Holly falls, injuring her leg. (Ironic that Cha-Ka was befriended by Holly when he himself injured his leg when trying to flee from Grumpy). Uncle Jack quickly lifts his niece into his arms, but the dinosaur towers over them, roaring madly, about to lunge at them. (Notice in this scene that the wrong dinosaur puppet was used; Grumpy is chasing them, yet they used the green Big Alice puppet. Rumor has it that many props were destroyed in a fire after the 2nd season; maybe that was the reason, or maybe the special effects staff was just lazy.)

Will manages to save the day by stuffing a bunch of palm fronds into the lunging carnivore's mouth. The feat somehow keeps the dinosaur busy long enough for the Marshalls to literally stroll away from the danger. Once they are safe, Will notices Cha-Ka running off toward the Lost City. Jack believes that Cha-ka is searching for the family, so he instructs his nephew to go after the Paku boy. Will runs off to catch up with Cha-Ka, but the Paku has already reached the Lost City.

Cha-Ka sneaks past several Sleestak where he reaches the room with the God of the Pit. He manages to divert the Sleestak guard's attention by tossing a stone across the room. Cha-Ka then sneaks over to the obelisk by the pit's edge, where he wantonly topples it into the foggy depths. Several Sleestak, including the Leader, in the Library of Skulls realize that something is wrong when they hear the pit god's angry roars. With arms raised as if delicately tip-toeing across a wet floor, they rush down the passage toward the pit chamber. Meanwhile, Cha-Ka manages to reach the unguarded Library of Skulls and steals the Voice of Wisdom off the central pedestal. Before he leaves, he sticks the hunting knife into the top of the pedestal, proudly and fearlessly leaving clear evidence of his crime. As the possessed Paku heads for the entrance with the skull, Enik strolls by and happens to see him; the Altrusian calls out for Cha-Ka to stop, but the Paku ignores the request and flees into the jungle.

Outside the Lost City, Will searches for Cha-Ka, who happens to be hiding just around a pillar. The Cha-Ka throws his voice, falsely calling out for help, so Will rushes ahead to help his friend in distress. Meanwhile, the Sleestak discover the hunting knife atop the pedestal of the Voice of Wisdom; the Leader is furious, calling for revenge on the Marshalls. Enik tries to tell the Leader that it was not the doing of the Marshalls, but before he can mention Cha-Ka, the Leader pushes him aside. The Sleestak stomp off to seek revenge, and conveniently come across Will, who is searching the tunnels for Cha-Ka. Will predictably fails to flee quickly, giving ample time for the Sleestak to surround him. By the time Will reacts, he cannot break free of the Sleestaks' grasp; the Leader commands his guards to take their human prisoner to the Pit.

Back at the Temple, Holly and Jack find their quarters in shambles; as strange as it may seem, they are forced to conclude that Cha-Ka is responsible. Jack decides to go out on his own to find out what is keeping Will and Cha-Ka. Not far from the Temple, Jack finds Cha-Ka hiding in the bushes and grabs the little Paku before he can flee. Cha-Ka insists that he feels fine and demands to be let go; he even bites Jack in an attempt to break free. The Paku doesn't seem to put up much else of a fight, however, since Jack picks him up without much struggle and carries him back into the Temple to be put to bed. Cha-Ka makes up an unconvincing story about being chased by a wild pig, then denies having seen Will anywhere.

In the Sleestak Pit Chamber, with his wrists bound together, Will stands accused by the Sleestak Leader of stealing the skull. Will admits that the hunting knife is his, but adamantly denies knowing anything about the stolen skull. The Leader breaks open the bottom of a suspended sack filled with sand and threatens Will with the following demand: if he does not reveal the skull's location before the last grain of sand spills, he will be sacrificed to the God of the Pit. As the Leader charges off, Enik once again tries to speak, but the Leader denies the Altrusian any chance to reveal his knowledge. Instead, the Leader warns Enik that he shall be tried next if the human fails to make a confession.

Will struggles to cut through the wrist-binding rope by scraping it against a large rock, but unfortunately the Sleestak guards become wise to his efforts and tower threateningly above him. Will then pleads to be set free so that he can go out into the jungle daylight to find the skull. Back at the Temple, Uncle Jack and Holly are still baffled by Cha-Ka's behavior; he doesn't appear to have a fever, but keeps trying to run away. Just then Enik arrives at the Temple, where he questions Cha-Ka on where he hid the Skull of the Voice of Wisdom. The Altrusian explains to Jack and Holly that Cha-Ka stole the skull, and that the Sleestak have blamed Will. Enik goes on to inform them that Will is held prisoner in the Chamber of the Pit, awaiting his sacrifice. Jack is about to rush out to save his nephew, but Enik warns that a rescue attempt would be suicidal, since all Sleestak have been mobilized. The only hope, the Altrusian explains, is for Cha-Ka to return the skull immediately. Cha-Ka refuses to reveal where he hid the skull, refusing to aid either Will or the Sleestak. When Cha-Ka again tries to flee, Holly worries that he may have been poisoned by the beetle bite, prompting Enik to question her about the insect. Holly's description of the beetle confirms the Altrusian's suspicion: Cha-Ka has mistreated the sacred beetle known as "Tula", the same sacred scarab recognized by the ancient Egyptians. Those who mistreat it are cursed with behavior leading to eventual self-destruction; the only way to remove the curse is to atone by treating the same scarab with kindness. Before he departs, Enik urges the Marshalls to hurry, since the Sand of Time is running out. Holly remembers that they saw the beetle near the swamp, so they drag the uncooperative Paku out to find the scarab.

In the Pit Chamber, the Sleestak Leader is surprised by his captive's defiance, but ignores Will's argument that he had no reason to steal the skull. At the swamp, the Marshalls conveniently find the giant golden beetle. Holly hands Cha-Ka a flower to feed the bug, but when he is freed from restraint, the Paku escapes. He runs along the swamp's edge, where he nearly gets killed by LuLu; Uncle Jack luckily saves him from the menacing hydra. Jack pleads with Cha-Ka to recognize that the curse is making him self-destructive, and begs him to atone if he wants to save his own life. The shaken-up Paku manages to concentrate enough to feed the sacred scarab a flower, but then runs off into the jungle. He recovers the hidden skull from some bushes and rushes toward the Lost City.

The Leader begins the ceremony of the sacrifice in the Pit Chamber, but panicking Will manages to break free from the grip of the Sleestak guards. He manages to circle around the pit, but with hands still bound, he is recaptured while trying to climb over a boulder. Just then Cha-Ka, with skull in hand, dashes into the chamber where he hops onto a rock near the pit's edge. He demands that the Sleestak let Will go, or else he'll hurl the skull into the pit to shatter below. The Leader submits to the Paku's demand; Will's hands are cut free, and he is released. Will rushes over to Cha-Ka, where he takes possession of the skull and orders the Paku to escape. Will then holds out the skull while backing up toward the exit passage, and when he reaches it, he tosses the skull to the Sleestak and flees. Once the skull is secured in the Leader's hands, he orders his guards to go after their prisoners. The Sleestak hop goofily down the passage, but Will and Cha-Ka manage to make it out to the plaza. The Marshalls regroup on the Lost City plaza just as an electrical storm arrives; the lightning flashes prevent the Sleestak from pursuing the family further.

Back in the comfort of the Temple, Will and Holly play chess on a home-made board. Holly enjoys a rainstorm, though Will is quick to add that it helps to have an ample supply of firewood. When Jack then reminds his nephew that it is his turn to keep the fire, Cha-Ka lends a helping hand. In the ending gag of the episode, Holly asks Cha-Ka what he would like to be when he grows up; while the Paku ponders the question, Jack comments "probably not an entomologist". When Jack explains that an entomologist collects bugs, the whole family gets a cheap laugh.