Emma Carlson Berne 
Disappearing Otters [PDF ebook] 

Elsa Roth’s life at a seaside marine biology facility is about to change. Summer is coming to a close and there are new arrivals at Seaside Sanctuary: a group of otters. The adorable otters aren’t the only newcomers — a new group of volunteers is also starting at the sanctuary. When Warren, a classmate of Elsa’s, shows up in the group she’s less than thrilled. He’s been nothing but rude to her at school and doesn’t seem at all interested in animals. But soon Elsa has bigger problems on her hands. One by one, the otters start disappearing. Can Elsa get to the bottom of things before more animals go missing?