After Spear and Fang evade a pack of raptors in the savannah, they experience a red lunar eclipse. They encounter a tribe of primitive cavemen who are attacked by giant bat-like creatures. They attempt to fight the bat creatures off, but Spear is carried away by them, his spear being left behind with the cavemen. Fang pursues the bat creatures to a massive vertical stone pillar, which she finds impossible to climb. Seeing bat creatures emerging from the top, she plays dead and allows them to carry her to a cave at the peak. While searching for Spear, Fang discovers humans webbed up and decayed, as well as a massive spider. Spear, cocooned in webbing, awakens and helps Fang kill the spider. As the bat creatures return, Spear and Fang use the spider's webbing to safely descend the pillar. Spear retrieves his spear from the cavemen as he and Fang flee from the bat creatures. They lead the bat creatures into the savannah's tall grass, where the bat creatures and the raptors attack one another while Spear and Fang safely escape towards the rising sun.
Tropes featured in this episode include:
- Animals Not to Scale: The raptors are slightly oversized, the bats are orders of magnitude larger than the biggest species in the fossil record, and the spider is humongous.
- Androcles' Lion: The ape man carrying food breaks his leg and is vulnerable to the giant bats that prey on them. Spear runs out and manages to carry the ape man and his food back to the safety of the rocks, albeit forgetting his spear. At the end of the episode, the rescued ape man had taken in the weapon and gives it back to Spear while he and Fang flee from the bats.
- Bad Moon Rising: A lunar eclipse (the eponymous "blood moon") shows that the bats are about to attack.
- Bat Out of Hell: Spear and Fang fight a flock of gigantic red bats in the episode.
- Behemoth Battle: The fight between Fang and the Giant Spider, although it's rather one-sided in the spider's favor.
- Chekhov's Gunman: The raptor pack that Spear and Fang flee from in the tall grass become important in their escape strategy from the flock of bats, as the duo lure the bats into the same tall grass where the raptors engage them.
- Cue the Sun: The episode ends this way, with Spear and Fang running towards the sunrise after surviving the night.
- Curb-Stomp Battle:
- Fang's battle against the Giant Spider has the giant spider easily smash Fang against the wall several times and nearly kills her if not for a Triceratops horn through its head courtesy of Spear.
- When Spear and Fang lure the bats into the tall grass where the raptors live, the raptors have a far easier time against the bats than vice-versa.
- Dark Is Not Evil: The gangly, albino cave-dwelling hominids are very much team players, giving Spear back his spear when he and Fang evade the furious bats.
- Decapitated Army: Subverted. When the bats realize that their Giant Spider leader was killed by Spear and Fang, the entire flock goes after the duo in full force.
- Did You Just Punch Out Cthulhu?: From the cavemen's point of view, Spear and Fang ride in at dusk, pick a fight with a pack of giant bats, expand the fight to all the giant bats, decimate both them and the local raptor population too for good measure, then ride off at sunrise leaving an unbelievable number of predator corpses in their wake. Now imagine the one caveman who witnessed all this trying to get the others to believe him...
- Evil Tower of Ominousness: The bats carry Spear to the prehistoric equivalent of this trope, a cave on top of a tall stone spire. It is the home of a Giant Spider who seems to control the bats.
- Frazetta Man: The tribe of sparsely haired, pale, cave-dwelling people are a subversion, as despite being primitive and ugly, they are not particularly savage and even help Spear in return for him rescuing one of them from the bats.
- Giant Flyer: The monster bats are larger than humans and strong enough to carry off full grown dinosaurs in pairs.
- Giant Spider: The main antagonist of the episode is a spider that's similar in size to a sauropod, towering over Fang.
- Homefield Advantage: The raptors are deathly afraid of the giant bats when they're out in the open, but when the bats are lured into the tall grass, the raptors gain a massive advantage thanks to the cover allowing them to ambush the bats.
- Horrifying the Horror: When Spear and Fang are cornered by a large pack of raptors, the rise of the blood moon causes the raptors to scatter, as it means the giant bats are out to hunt.
- Impaled with Extreme Prejudice: The Giant Spider is killed when Spear throws a Triceratops horn clean through its head.
- Metronomic Man Mashing: Or rather dinosaur-mashing. The Giant Spider grabs Fang by the tail and bashes her to the wall of its lair several times.
- Playing Possum: After Fang is unable to climb up to the rock spire where the bats took Spear, she pretends to be dead so that the bats carry her up onto the spire as well.
- Primal Chest-Pound: Pun not intended. An ape-man pounds his chest while screaming as he charges to the rescue of a tribe-mate.
- Raptor Attack: A pack of Jurassic Park-styled dromaeosaurids appear in the beginning and the end of the episode. They're large, scaly animals that hunt in packs.
- Roaring Rampage of Revenge: After the giant bats see that their Giant Spider leader has been killed by Spear and Fang, the entire horde immediately sets off after them.
- Set a Mook to Kill a Mook: Chased by a horde of bloodthirsty giant bats, Spear and Fang lead them into the tall grass where they are set upon by the raptor pack that had been menacing them in the beginning of the episode.
- Vertical Kidnapping: One bat swoops down and carries an ape-man away so quickly and efficiently that the audience can't even see what took him - just a red blur. Presumably, this is what happens with most of their smaller prey.
