Alan Beach is a Homicide detective. Jake Riley is a contract agent of the CIA.
They are when we first meet them. They will change a little bit as the short series progresses but for the most part, that is their lines of work.
Beach is in his late thirties, described further as carrying "a few extra pounds but certainly wasn’t fat. Of average height and medium build, he was always dressed in a well-cut, dark suit and tie. His sandy hair was neatly trimmed at the back and sides but the top was slightly tousled. The boyish hair, combined with vaguely rounded cheeks, made him appear younger than his age but his eyes betrayed an inner sadness." As of the first recorded adventure, he has been in Columbus Ohio for three years, moving there from Boston where he was also a homicide investigator until "the Incident" there made him a pariah in that department and necessitated a new home.
Jake Riley is a former member of Delta Force who was often seconded to the CIA, part of the elite Special Operations Group. Riley was severely injured in a mission to Laos resulting in "deep, jagged scar running vertically from above his right eyebrow to halfway down his cheek". Even worse was the damage to his right knee that require full replacement with a titanium one.
The two will each work a situation from their own end until they come together.