When a mysterious criminal known as "Mortus" murders her old friend, Dejah Thoris goes against her grandfather and father's will and journeys to the dangerous Red Man city of Zodanga to uncover the truth of what happened. She forces a secret operative from her government to take her on as a partner and together they assume the guise of an assassin and his slave. They penetrate the seedy underworld of Barsoom’s most crime ridden city and join one of the assassin guilds as they play a dangerous game to learn Mortus’s true identity. Dejah gets more than she bargained for when Mortus is finally revealed and she comes face to face with the mechanical monsters known as the Machine Men! This volume collects issues 20-24 of the hit series by Robert Place Napton, Carlos Rafael, and Debora Carita, as well as all of the covers by Paul Renaud and Fabiano Neves.