Michael Alden is an agent of - well, therein lies the mystery.
Onboard a luxury liner just docked in New York City, a man who was noted as being called 'Gigot' is waylaid by a woman and two men with the proclamation that they knew what he was planning, that he had betrayed them, and they were decidedly unhappy about it. They drug him, take away all forms of identification, and then toss him off the ship in the river expecting him to die. He disappointed them and managed to make it to short but the only words he spoke initially were the cryptic 'Coronet Blue'.
It becomes clear to all including him that he has no recollection of who he is or how he got in water. Needing a name, he combined that of the doctor attending him and the hospital he was in, coming up with Michael Alden. He left the hospital prematurely and set off to figure out the truth of who he was, using as his only clue that interesting phrase.
Along the way of his investigations, Alden will find friendship with Max Spier and temporary part-time employment washing dishes at the man's restaurant, 'The Seeing I'. Alden also befriends a monk named Brother Anthony. Both men will assist in at times when he asks for assistance.
Making understand the facts about himself becomes a very urgent matter when it becomes clear that a group of people known as 'Greybeards' are out looking for him in the hopes of finishing his demise.
The man calling himself Alden is in his late-20s or very early 30s, best described as "a brawny, firm-jawed, sandy-haired" man standing 6'2" tall and in fairly good shape with a winning smile and manner.
Those viewers following his steps are never told the truth as to who Alden was or why he was being pursued but Wikipedia reports that the series creator, Larry Cohen, told his biographer: "The actual secret is that Converse was not really an American at all. He was a Russian who had been trained to appear like an American and was sent to the U.S. as a spy. He belonged to a spy unit called 'Coronet Blue.' He decided to defect, so the Russians tried to kill him before he could give away the identities of the other Soviet agents. And nobody could really identify him because he didn't exist as an American."