The Old Sapphire Processing Plant

 is a Sunless Sea Story Event.

Trigger conditions
This event becomes available in Port Carnelian if you have the Zubmariner expansion and the following:  A Zubmarine Zecret = 1 Zubmarine = 0

Story description
It sits on an inlet at the port's edge. Here, the Fierce Philanthropist runs an illicit but profitable business converting ships into zubmarines. After all, philanthropy doesn't come cheap.