Scooby-Doo: Origins.

During their final summer at camp, old friends Shaggy and Daphne get embroiled in a haunting mystery surrounding a lonely, lost Great Dane puppy who may have been a witness to a supernatural murder. Alongside the pragmatic and scientific townie Velma and the strange but ever-so-handsome new kid Freddy, they set out to solve the case that's pulling each of them into a creepy nightmare that threatens to expose all of their secrets.