Three years after the Sacking of Coruscant, Darth Malgus receives an order to find an ancient Rakatan artifact that has caught the attention of the Sith Emperor. Located on Earth in the Unknown Regions, the retrieval of the artifact will improve Malgus's Imperial status and help him with his secret plans, but he must fight his way through zombies and Republic forces to get it.

Darth Tenebrous and Darth Plagueis were on their way to Muunilinst in their starship when they woke up to find themselves caught in an unknown planet's atmosphere. Little did they know, Darths Bane and Zannah once lived in the Underworld and brought hell to the mythologies. Will Tenebrous and Plagueis find a way back to their home galaxy like their predecessors once did?

Darth Bane and Darth Zannah began to fight each other on Ambria for the mantle of Dark Lord of the Sith when everything suddenly went black. They awoke in the Underworld, one of many worlds among the mythological factions. The Sith Lords must survive at all costs if they are to continue the Sith's lineage, starting with finding a way back to Ambria.