Harbour Bay, renowned throughout Nysonia for its towering alchemical laboratories and innovative spirit, faces an unprecedented crisis as a mysterious plague sweeps through its districts. Citizens initially develop severe illness and ashen gray skin before transforming into seemingly normal but homicidal versions of themselves, attacking former loved ones with brutal efficiency. The Emperors Council, desperate to contain the outbreak, hires the adventurers to investigate—pointing them toward the notoriously ambitious Varlian family of alchemists, whose recent secretive experiments have drawn suspicion. What the Council doesn't reveal is that the military has already determined the only solution: quarantine the city and eliminate all infected individuals before the contagion spreads beyond control.

As the adventurers navigate Harbour Bay's panic-filled streets and rival alchemical laboratories, they discover a far darker truth—a rogue alchemist has deliberately engineered this plague as a devastating weapon to sell to the crown for an enormous profit. With time measured in hours rather than days, the adventurers must piece together clues from competing alchemical families, sabotaged laboratories, and encrypted research notes while fighting off waves of infected citizens whose numbers grow exponentially with each passing hour. The final confrontation will take place in the culprit's hidden underground laboratory, where the adventurers must defeat the mad alchemist, secure any existing antidote, and make a devastating choice: attempt to save the remaining uninfected citizens, or ensure the plague weapon never leaves the city—even if it means condemning Harbour Bay to destruction.