Three young couples get their hands on a growth formula developped by a local nerd. Their initial intention is to make money out of it, but things will get out of control when they decide to try it and find out that it only works on females. The three girls will show that despite being friends have very different characters.

This is the third and last part of the Side Effects trilogy.

Volume 3 takes over right after the end of Volume 2. 

After having been reduced at the end of Volume 1, Kelly, Lisa and Casey are giant again in Volume 2, this time in a big city. They are all 250' tall, but Kelly has known for some time what's the force behind their growth. Fearing that her plans of using her size to rule and have fun are threatened by her former friends, Kelly will make herself much bigger than them and lets them know that she will be the one in charge from now onwards. She is tired of Lisa's naiveté and Casey's mindless violence.

At the end of Volume 2, Kelly uses her newfound size to defeat an army attempt at her and destroy the research center that could threaten her power. Once she is done, she sets on a quest to take over the world. This is what she will try to do in Volume 3. 

Left behind, Casey will set herself on a mission to become as big as Kelly, to be the one on top again. In the meantime, Lisa will try her best to stop her former friends and protect her family.