Heart of Stone — Gail Dayton

The king's champion, Harald Aldred's Son, is sent to a strange and terrifying universe on a quest to save his world. Dragons are one thing; 18-wheelers are something else entirely.
Shayna MacAvoy is trying to sort out her feelings about the sort-of proposal she's recently received when a bleeding man in black chainmail falls at her feet. The first aid she provides him becomes only the first step on a journey that will take them deep into the mysteries of magic, love, and honor.
Harald's quest takes them across the farms, forests, mountains, and ancient lava flow deserts of Idaho on his search for the stolen Heart of Stone...