"From side to side it turned its head, a head that was a perfect sphere of silver.
"If the silent figure had any face at all, it was the face of the man in the moon!"
Now Thatcher has to make his theft under the watchful eye of his partner, while, unbeknownst to everyone, his fiancee starts poking into his organization. Will the Moon Man escape with the money?
"The Sinister Sphere" is mostly a structural story, setting up the Moon Man, the glass mask gimmick, his helpers and foes, and the complex relationships of a gentleman thief hiding in the open. So the actual caper is serviceable, but nothing special. The main allure lies in whether Thatcher can juggle the deceptions needed when his very family is dedicated to the Moon Man's capture. And, in the first appearance, he is able to. But the webs of deceit will tighten around him as the series progresses.
All in all, "The Sinister Sphere" is a nice B-side chance of pace to the more familiar hardboiled and hero pulps.