Can you actually kill someone with kindness?

Charity's acts of kindness always end in disaster, but when one clown costume too many lands her in the Vice Principal's office, she receives a mysterious note from "The Cassandra Coalition" offering to help get rid of her curse.

The coalition members all have the same curse-which just happens to attach itself to kind 13-year-olds-and it seems to be coming from the greyscale mirror world of Delphos-which just happens to be portal-connected to their hometown. As the curse expands, and people start turning into zombies, they suspect a full Delphos invasion is looming.

But when Charity's best friend goes missing, the coalition realizes they must track her down, close the portal, and find a way to end the curse-before it ends all of them.