In a couple seconds, another Black Knight Titan will spawn there and if you’re not across the bridge in time, you’ll have seven souls gold to do battle with another one.

From the location of the bridge, head south and east along the river until you see a Fisherman (he should be holding a fishing rod). Ask him if he has any idea on how to get inside the castle. He’ll tell you to ring a bell outside of the castle.

After the talk, head southwest and up the cliffs to the castle. You should see a Grail bell lying on the ground. If not, go back and talk to the Fisherman again. Ring the bell.

The Grail maiden will give you access inside the castle. Open the door directly south of you. Climb up the staircase and talk to The Fisher King. Say “you don’t look too well”.

The Fisher King replies that his son, Percival, Knight of the Round Table, has not yet returned. Your character will then suggest that you go find him.

Head back downstairs and acquire the Magic whistle to the north (make sure that you have 2 Magic whistles with you right now). Blow on one of them to be teleported back to the location of the four pillars.