A distinctly odd Chandler novel, in his weird slip into other dimensions type style.
Here, apparently a sequel to The Coils of Time of sorts, the idea is that in another coil, the Mars of Brackett or Burroughs or Bradbury might exist in some form, as it is just another time being remembered incorrectly by those writers.
With some modification to a ship and time machinery, they manage to investigate. The only problem is they do get somewhere Barsoom-like, complete with a Carter, Tarkas, and a Thoris analogue, but they are enslaved by H. G. Wells Martians!
None of them are too good with a sword, either, and one ship against opposition airpower may not be able to make much difference.
3 out of 5