Dejah Thoris, the fearless princess of Mars, faces a dreaded adversary from her past! Senneth Dor, the former Jeddak of Yorn, has returned... leading an unstoppable army of Machine Men on a march towards Helium! How will the princess be able to marshal the forces of her beloved city-state against the clockwork terrors when one of her most trusted allies has been conscripted into service by the enemy?