Arachni

A disease called Arachni has been spread through spiders around the world. Where you've been bit, your skin bubbles, and your veins turn into a yellowish orange. Hallucinations occur a few hours after you've been bit. Without warning, you lose all of your humanity and your emotions become nonexistent. You then begin to have the urge to kill animals and humans for sport.

Ava Woodland and a few of her friends are immune to the disease, but that also makes them more of a target to the infected.