The Sisterhood was an ancient guild of warrior women who wanted to eliminate all men and inferior women (women who were not chosen ones) and gain their place as the true rulers of the world.
Ariel is the leader of the Sisterhood, and in order to make the Sisterhood ascend, she invited the members to wrestling matches (called Women of Wrestling, or WOW) and hypnotized them with her stone. It turns out that Samantha (and all the women are on her mother's side of the family) are some of the descendants, as Sam's great-great-great grandmother was one of the chosen ones.
In the episode "W.O.W.", a group of women are attacking men and unrelated women. Sam is in the family line of the Sisterhood, so she is affected. After the wrestling match, Alex steps in Ariel's footprint. Later, she scans her shoe to find out where Ariel went with all the warriors. Her footprint is made up of 100 percent volcanic ash only found at Mount Saint Helens. Sam attacks the girls because they are enemies of the Sisterhood. During the fight, Sam gets covered in mud that blocks the power of Ariel's stone. The girls then fight Ariel. Using the belt's stone and the moon's position, Sisterhood members all over the world attack people. The Wind Tunnel 3000 Tornado Blast Hair Dryer is used to blacken the stone, allowing the spies to destroy it. Ariel vows that, "I'll be back, and the Sisterhood shall reign supreme".
The stone that was the source of the Sisterhood's power had to be used when the first full moon of fall appeared. Ariel escaped, but the destruction of the stone was a severe loss to her power.