Road Trip of a Lifetime

Meagan was currently on a road trip driving to a place all the way across the country. She had been hearing some weird noises in her trunk ever since she stopped at an inn a day ago, but she chalked it up to the car being its old crusty self. All of a sudden, one of her car's tires pops, and she stopped on the side of the road to change it. Upon opening the trunk, she discovered three little dogs snoring. When she went to pick one of them up, however, she realized it's actually one dog with three heads. She inspected the collar around the middle head, and it says CERBERUS, ONE HECK OF A BIG BOI, IF FOUND PLEASE RETURN TO UNDERWORLD (666) - 666 - 6666.

*Story idea taken from a writing prompt page and expanded on