Duke knew that the Crawford Family must have sensed something. They had surely learned of Bell's death and, in that brief instant, detected the location of the curse on Duke's side.
They had most likely learned the exact location, though the time had been too brief for Duke to know whether they had managed to pinpoint his position in that instant.
Harbor City alone was enough for the Crawford Family to determine a great deal.
This was Black Sail's territory and one of the locations of the Void Corridor's teleportation arrays.
The curse had appeared only fleetingly, and it had surfaced in Harbor City. The Crawford Family could therefore almost certainly conclude that Black Sail had killed Bell.
That was assuming the Crawford Family had captured that fleeting information. Otherwise, as long as the curse's power on Duke could remain suppressed, the Crawford Family would not yet know who had killed Bell.
Samuel definitely knew they had done it, but they could never have imagined that Bell had been angered to death by Duke.
Samuel naturally had ways to deal with his own family's curse. He simply had not gotten the chance to kill Bell himself before fleeing.
Duke and Merrick then split up. Duke went to find Lady Hela, while Merrick returned to look for a way to resolve the curse.
He quickly contacted Lady Hela, but she did not reply. Perhaps she was brewing potions and could not spare the attention to answer.
With time running short, Duke could only contact Leila and send her a message. "Leila, is Lady Hela there?"
Leila was still working for Lady Hela, handling tasks such as potion brewing.
Leila happened to be free and replied quickly. "Teacher has already left. She went to another plane and seems to have joined an