Hamlet and the Queen are talking about King Hamlet and Hamlet expresses his anger towards the queen for what she has done. The queen gets frightened by Hamlet and yells for help.
I could not forgive you for marrying Claudius!!
Polonius is behind the curtain hearing the queen ask for help and Hamlet stabs him through the curtain mistaking him for claudius as he is coming to help the queen.
what have you done!
The ghost appears and tells hamlet that his true purpose is to get revenge from Claudius and to take care of the queen. " O, step between her and her fighting soul: conceit in weakest bodies strongest works: Speak to her, Hamlet. Act3 Scene4 Line129-131 said by King Hamlet.