Final Fantasy II/Mission to Fynn Castle

Fynn
Everyone has moved to an encampment outside below Fynn to begin preparations for taking back Castle Fynn. Enter the encampment and speak to Princess Hilda and Prince Gordon. Enter Castle Fynn and collect all the treasures on your way up to the top floor. Defeat the monster at the top floor and the castle will be recaptured. Speak to Princess Hilda and Prince Gordon. They will tell you that Minwu has left for Town of Mages - Mysidia and has gone uncontactable for too long a period. They will send you to find him. At the same time, Princess Hilda will tell you about the White Mask and Dark Mask, one of which is hidden in the basement of Castle Fynn. Speak to Prince Gordon about the masks and he will tell you that Paul who resides in Fynn Town (bottom left corner) knows of how to enter the secret room. Paul will say that the entrance is to the far end of the audience room, to the right of the throne.