Rebecca Cadwell tends to slip on a false, dim-headed facade in school--a habit which explains her toxic friend group and her rather egotistical boyfriend, Dave. However, in the privacy of her poster-strewn bedroom, she spends hours wading through the grand expanse of Tumblr's Star Wars fan pages and squanders her Friday nights sneaking off to local cosplay events while her squad crashes house parties. This suppressing way of life encourages her to seek companionship from a supposed doppelganger she meets on Wattpad after Dave's "Girlfriend Challenge" YouTube video goes viral. After a few instant messages and photos are shared, the two girls quickly become determined to meet one another and conclude whether they're actually biological sisters. What Becca doesn't know is people aren't always who they appear to be.