I was a fan of Robert Arthur Jr before I was a fan of anybody else. Robert Arthur Jr came before Jack Williamson and Robert Howard and Fritz Leiber and Jack Vance and Roger Zelazny and Michael Moorcock and all the rest.
This because the first books I cut my teeth on were part of the series The Three Investigators, that were credited to Alfred Hitchcock but were actually written by various authors – and Robert Arthur Jr wrote the first dozen or so.
Robert Arthur also edited a number of anthologies, including Alfred Hitchcock’s Ghostly Gallery, that was – as I mentioned a few days back – the book that started my long-time fascination with ghost stories.
The volume included three stories by Arthur, The Haunted Trailer, The Wonderful Day and Obstinate Uncle Otis. Very good stories, that remained in my memory these 39 years.

Robert Arthur was a solid writer and (quoth Wikipedia)

His stories were published in Amazing Stories, Argosy All-Story Weekly, Black Mask, Collier’s, Detective Fiction Weekly, Detective Tales, Double Detective, The Illustrated Detective Magazine, The Phantom Detective, The Shadow, Startling Stories, Street & Smith Street & Smith’s Detective Story Magazine, Thrilling Detective, Unknown Worlds and Wonder Stories.

I devoured his kids mysteries, and I greatly enjoyed his ghost stories, so I’d love to read more by Arthur, but so far I’ve been able to track very little.
There’s three stories on Project Gutenberg, and then it’s all a matter of sifting through piles of used books in flea markets and what else.
But here’s the good news: Robert Arthur was also a writer for radio and TV. On the telly, he contributed to The Twilight Zone, Alfred Hitchcock Presents and Thriller, and on the radio he got two Edgar awards for his work, and wrote for a number of shows, and he both wrote and directed The Mysterious Traveler.

The Mysterious Traveler was an anthology series that ran between 1943 and 1952, the Mysterious Traveler of the title acting as host and narrator, like what the Shadow used to do at the very beginning of his career. It was the show that landed Arthur his second Edgar Awardd, in 1953.

This is the Mysterious Traveler, inviting you to join me on another journey into the strange and terrifying. I hope you will enjoy the trip, that it will thrill you a little and chill you a little. So settle back, get a good grip on your nerves and be comfortable—if you can!

The traveling mate from hell, the Mysterious Traveler was announced by a train whistle, and then he’d start telling a new story. Fittingly considering Robert Arthur wide spectrum of genre writing, the stories ranged from mysteries to science fiction to horror and fantasy.
The public was entertained, and a digest magazine was also published.
A total of 370 episodes were broadcast, but today only 75 survive, with titles such as House of Death, The Man Insects Hated, No Grave Can Hold Me, The Man From Singapore, The Planet Zevius.
And we’re lucky enough, because the surviving episodes can be found on the Internet Archive, that also holds a few issues of the comic book that was produced to tie-in with the series.

So, while my hunt for more Robert Arthur stories continues, now I have the Mysterious Traveler to keep me company.