Isabelle is forced to call on Styx for help and ventures into the lion's den. Doctor Vrancken feels like a complete failure but finds a surprising ally. And the Viking finally steps out of the shadows of the underworld...

An unexpected collaboration brings Styx closer to the truth than ever. In a final confrontation, the masks finally fall off. But the consequences are horrific. The gates of the realm of the dead seem to close behind Styx...