Whitey Harrison is an agent with American Intelligence.
We are told in the first recorded adventure that he is "Uncle Sam's trouble-shooter in the Orient!" Or at least he will be right after our introduction as we are there to watch his Chief give him the new assignment, which he accepts eagerly with a "Swell - I'm itching for action!".
He is given this new mission at F.B.I. Headquarters in Washington with the Chief telling him, "You've been doing a nice hob for the Secret Service!" This is a tad confusing then since the traditional Secret Service, then a part of the Treasury Department, would not have such activities going on in the FBI HQ, a part of the Justice Department. Toss in the fact that at the time of this reassignment, 1940, it was not uncommon for narrators to lump any and all intelligence work down in the U.S. under the umbrella of 'Secret Service' as a euphemism for any and all spy activity. However, he will soon be telling a stranger that he was "from the F.B.I." so who knows? Especially when in a later adventure he is clearly again identified as working for the Secret Service.
Whomever he actually works for, Harrison is told he is now handling "one of the most important assignments we've had in years", one in which "American interests must be protected and yet friendly relations with these countries must be maintained!". It is important to remember this was before April 1940 so while the War in Europe had begun, the War in the Pacific, as far as America was concerned, was still 20+ months away.
Harrison, a tall, thin moderately handsome man with short blond hair brushed back, was told that he would have one assistant to work with him and he was free to make the choice himself. With little hesitation, Harrison mused to himself that "good old Blackie will be just the man for this job". This Blackie is a short, almost emaciated fairly odd looking fellow with an impressive skill at disguise, complete it would seem with a firm grasp of Chinese.
A month after getting the new job, Harrison and Blackie are stationed in Shanghai where they receive their first mission. One point to note is that Harrison is seen dressed in a Navy uniform and he will continue to wear it throughout that harrowing case, even when it means heading Japanese controlled part of China. Blackie would also join him in that type of attire though Blackie was more prone to casual wear.