Adam appears briefly in the first book when Guy takes Jimmy on a romantic dinner out to Adam's Sierra Bistro. Once a famous San Francisco chef, Adam abandoned fame and started a small restaurant in the foothills of Northern California. He serves what he wants and diners either eat it or they don't.
The mystery is why Adam decamped from the city and what happens when his past comes back to haunt him. To tell the story, I've introduced Jason, Adam's former lover; Little John (aka L. J.), Adam's current sous chef; and Damon, the teen Adam's mentoring.
So far, this is the way the book starts out. This is subject to revision, however. It's early stages and I'm only 11K into writing the book. So this may or may not be included in the final copy.
Barnes and Noble