Chapter 2 Stuck in Tyrine sewers!!

I have got as far as the area where one saves the girl lost in the sewer, and saved her. Unable to get any further as the way forward is blocked by what looks like an area of water in the passage, which stops me going forward.
My party consists of Cocka, Sarah, Brussian, and Random of course.
What am I doing wrong please??
According to the walkthrough I should be able to go on and defeat a monster that used to be a man, and then find a switch. No monster and no switch. Am I misreading the direction to go? The area where the girl is located is a dead end. This is the main quest to clear the sewers, after having cleared the top part (Quest 25.)
I really could use some help please!!!
My party consists of Cocka, Sarah, Brussian, and Random of course.
What am I doing wrong please??
According to the walkthrough I should be able to go on and defeat a monster that used to be a man, and then find a switch. No monster and no switch. Am I misreading the direction to go? The area where the girl is located is a dead end. This is the main quest to clear the sewers, after having cleared the top part (Quest 25.)
I really could use some help please!!!
