When Worlds Collide — Amy Laurens

This is what the fairies never wanted you to know…

Edge Tanning gets things done. She vanquished the shadows that were threatening Sanctuary, she saved her best friend from the Valley -- and she called the power of Sanctuary, magical home of the fairies, to life. So now that Sanctuary's broken, obviously, she has to fix it.
Only problem is, she's not used to working alone -- and this time, none of her friends want to help. In fact, when Edge senses Sanctuary mysteriously appearing around her while she's at school, her friends won't even believe her.
And that's before she learns that time in Sanctuary isn't just running out -- it's skipping sideways. This may just be too big for one teen girl to handle.

Brace yourself for the exciting conclusion to the Sanctuary series: this is what the fairies have been hiding.