Mesa of Lost Women

Tarantella's spider-like claws caress Doc Tucker and end in his lifeless collapse, followed by a chilling kiss. A disembodied voice asks the audience, 'Have you ever been kissed by a girl like this?'

Frank and his Mexican assistant Pepe find Grant Phillips and Doreen wandering the Muerto Desert, severely dehydrated and exposed, and rush them to the oil company's field hospital. As Phillips begins to recover, he feverishly asks for an oil truck expedition to destroy the secret 'super bugs' from Zarpa Mesa's underground laboratory. A narrator interrupts his story and shifts the focus to Pepe.

One year earlier, famous scientist Leland Masterson arrives at Zarpa Mesa at the invitation of reclusive Dr. Aranya. Aranya reveals his growth hormone experiments, creating human-sized tarantulas he can telepathically control and spider-women. His goal is to breed spiders with human intellect under his dominion.

In response to Masterson's dissent, Tarantella injects him with a drug that leaves him simple-minded. The injection marks Masterson as a puppet for Aranya's broader plan to dominate the world.

Masterson enters a lively border bar where Jan van Croft and his fiancée Doreen celebrate. Tarantella's hypnotic dance captivates everyone except George, a nurse from the asylum who has come to collect Masterson. Masterson shoots Tarantella, then forces Jan, Doreen, and George onto Jan's aircraft.

Tarantella regenerates after an apparent death and slips away from the bar, free to pursue her victims once more.

Masterson coerces the hostages to depart in Jan's aircraft, ignoring the plane's disrepair. Grant Phillips and Wu join the flight as additional passengers, with the plan to reach Zarpa Mesa.

Wu sabotages the airplane to ensure Masterson's return to Aranya's side. Tarantella's spider-women then kill Wu, removing him as a threat to the plan.

Engine failure and a misread compass force a crash-landing on Zarpa Mesa. George is killed while exploring, Jan is wounded, and Grant and Doreen struggle to survive as the desert narrows in around them.

The survivors are captured by Aranya's spider-women, and Masterson's intellect is restored, making him useful to Aranya's experiments. He agrees to help in exchange for a chance to influence the outcome.

With his restored mind, Masterson helps devise an explosive in the laboratory while Grant and Doreen manage to escape the collapsing situation, fleeing Zarpa Mesa.

Masterson detonates the explosive, incinerating the laboratory along with Aranya and the monsters. He dies in the blast as the lab and its horrors are reduced to ashes.

Back at the Muerto Desert field hospital, Grant's story is met with skepticism, with only Pepe believing him. It is revealed that Delores Fuller, one of Aranya's spider-women, has survived.