Hart Muldoon is a freelance agent.
The period of time of his activities is the late 40's throughout the 50's. The location of his activities is largely centered in and round the Riviera, at least when he is not working. When he is on the job, he could be found anywhere in Europe and the Middle East, and during the final adventure we have of him, the Caribbean.
All of these locales are warm (or hot) and sunny climes so it is amusing to hear him wax nostalgically numerous times for his long desire to head back to the States and take up retirement residence on a farm in Maine.
While one reference indicated that he thought of himself as Irish, Muldoon is that only in his ancestry as he is clearly American in origin and still considers the U.S. his home. And apparently so does the IRS because he is informed a time or two that they would like to discuss with him his earnings over the past decade while living abroad.
Muldoon's activities can best be summed up by three statements from various adventures.
The first is from a female who claimed to be a reporter and who revealed she knew him to be a "boy hero in the O.S.S. during the Second World War. Gone bitter with the sight of the business-as-usual boys. Stayed in Europe as a free lance. Handled some dangerous assignments for various individuals and governments - some of them odd jobs for odd individuals and odd governments."
The next is from his own lips when he admits, "since the end of World War Two I'd stayed on in Europe watching - with what I told myself was cynical indifference - the world falling apart. I'd been wrapped up in dirty deals for dirty squares and shaky governments, out for hire to anything this side of the Iron Curtain and to anyone who could come up with a reasonable price."
And finally from a British spymaster who has used him several times, "sad that at your age and with your experience you should still carry with you the delusion that you can return to decent society ... You and I - we belong outside. We belong to the hunters and the hunted. We belong to a world of violence and deception, a world that makes its own laws. We lie and we steal and we kill because it is our job to do it. And you can't go back, Hart, you simply can't go back."
Muldoon would very much love to prove that last one wrong, despite how much he knows it to be true.