Swords of Mars is the eighth installment in the Martian tales of Edgar Rice Burroughs. It differs from the previous books in that it doesn't start with a kidnapping. Instead, the action focuses on John Carter as he goes undercover to infiltrate and destroy the criminal Assassins' guild that threatens the peace of Mars. Carter works his way into the confidence of the criminal bosses, at which point he learns the secret plot of the Assassins' guild: they are going to kidnap Dejah Thoris, John Carter's wife.

John Carter is unable to stop the kidnapping, but he follows her to the moon Thuria, where her captors have taken her. On Thuria, John Carter fights a horde of invisible enemies and rescues Dejah Thoris.

Swords of Mars is an excellent book, but it suffers from abrupt plot resolution syndrome (APRS). Everything is fine until Burroughs suddenly and without warning wraps up all the loose plot ends and finishes the story, all in the space of eight pages. Swords of Mars was first published as a six-part serial in The Blue Book Magazine. I can only imagine that Burroughs must have failed to plan ahead, and had to cram too much plot into too few words when the sixth and final installment came due.

Swords of Mars is out of copyright in Australia but not the United States. You can read it online at Project Gutenberg of Australia.