Leave this area back to the starting door of the wall area. Go up the ladder and pull the lever. The final drawbridge goes down. Go down teh ladder, in the door, cross the bridge. Go back to the main gate and save. Go to the gate. The girl opens the gate and falls over. The gate opens up and a bridge extends. Walk across with her, but a light zaps the girl and the bridge breaks between you. You jump to her, losing your sword and she catches you. Then all is dark.

The Ico Walkthrough

Please swing by my Forum to ask me how to get through if you're stuck somewhere I haven't put up yet. I'll get back to you quickly.