Megan Atwood 
Grabbed by Greys [EPUB ebook] 

Kaci and Abby are not BFFs. But when a joint family camping trip throws them together, the girls must make the best of it. Luckily, a rickety old amusement park down the road provides the perfect distraction – until Kaci mysteriously disappears for two hours in a fun house. Abby is furious – but then she experiences a bizarre time-lapse of her own. Determined to figure out who is behind their otherworldly abductions, the girls set aside their differences to work together. Soon their close encounters make them BFFs of a different kind – best friends in fear!