Thomas R. Sloane III, aka a Man Called Sloane, is a freelance agent with the UNIT.
First, the UNIT is a secret organization which is part of the American Intelligence community. It is run by a man we only know of as the Director and, according to him, orders for the UNIT come directly from the President and only he can authorize the UNIT to take action. [Note: I have seen the name displayed as an acronym, U.N.I.T., but I have seen no breakdown for that and no evidence one way or another.]
The UNIT has its headquarters in, apparently Los Angeles, using as its front an ordinary-looking store called "The Toy Boutique". The insides show it is in fact a toy store. However, if a visitor were to go to the fuse box on a wall, flip the top level to the down position which slides that panel down revealing an electrical id device using voice recognition. With an authorized name, a door opens allowing access a series of offices, including that of the Director.
The Director has a staff, of course, but his key source of information and analysis is "Effie". We never actually meet her, only hearing her voice throughout the headquarters, but we are told she is a "EFI series 3000 multi-function computer", occupying 27 square feet and weighing 6 1/2 tons (this was 1979). According to the Director, the very alluring voice comes thanks to the efforts of Sloane, though how is not mentioned.
While the UNIT is empowered to go after any enemy of the country ordered by the President, it has a rival group, a nemesis organization, named KARTEL. [Note: again I have seen this spelled as an acronym, K.A.R.T.E.L.] Exactly who makes up this criminal organization is not known, just that they are bad guys doing bad things.
Sloane is described by other sources as being a freelance agent. This likely derives from his having, in the pilot adventure we have of him, running his own business, an art and antique business, and taking on missions for the UNIT 'on the side'. In the subsequent adventures, I did not see any reference to this business but I could have missed it.
Sloane is a very good looking man of around 40 years of age. He is in terrific shape and not in the least afraid to mix it up with a bad guy or two and his fighting skills good enough to come out on top. He is also fit enough, and handsome enough, to consistently attract the attention of virtually every female he comes in contact with, including the artificial intelligence named Effie. We do not see a lot of Sloane in his off-time but when we do, he is not alone.
Sloane has a nice assortment of really cool gadgets at his disposal, including a mega-tricked up two-seater sports car which has a water spray cannon in the back capable of unleashing an impressive amount of water (no idea where the tank is).
In the pilot adventure Sloane has to go up against a KARTEL exec who has as his lead henchman an impressively tall black man named Torque who has a steel right-hand with a nice set of changeable tools. He is darned good at being a bad guy but he, unfortunately for him, met his end when he had a final run-in with Sloane who turned his steel hand against him and tossed him out a window to fall 1,000 feet. When the remaining adventures start up, Torque is very much alive and is obviously a very close friend to and ally of Sloane. Not sure what happened during that plunge but it was obviously traumatic.