Bill Cartwright is an agent with Operation Hang Ten.
The trouble with discovering the espionage work by other nations taking place under cover of the youth movement is that trying to sneak agents into the teen scene almost never works. The premise behind Operation Hang Ten, a small intelligence agency created just for this purpose, was that the best infiltrators were those already inside. In a 'Mod Squad' approach, the head of the organization has drafted several young adults who were established in the region.
Chief among his young agents was William Cartwright. Born in November of 1945, Cartwright joined Hang Ten in 1966. After a childhood spent along the beaches of California, Hawaii, and Australia, his love of surfing was firmly implanted and he had won several championships in his younger days.
When his parents died and left him over ten million dollars, Cartwright knew that working was something he had to do only is he wanted. But the excitement of his cover-job, that of a private investigator, coupled with the danger of the intelligence work, has made Cartwright the best that Hang Ten had to offer.
The write-up on the back of the first chronicle truly sets the mood for the character as well as the style of action to be found in the books:
'Four paternity suits. Three breach of promise suits. No conviction so far, but give him time. Hobbies: surfing, women, and, whenever possible, poking a crooked finger in the hairy eyeball of the Establishment. Vocation: Secret agent for the United States Government.'
By the way, virtually every book has the head of the organization instructing his secretary to contact Cartwright by using the special phone and dialing 'six zero dash six nine'.