In Act 1 Scene 5 the ghost reveals to Hamlet that he is indeed his dad but Hamlet is not sure whether to believe him or not. The ghost goes on to say that Hamlets uncle who is the king right now after he married Hamlets mum his dads wife. He goes on to say that he killed him by putting poison in is ear. After he explains how the new king killed him he says he wants revenge and wants it now. Hamlet then starts to believe the ghost that he is actually his father so he promises to avenge his fathers death, the ghost also says not to do anything to the ghosts wife Hamlets mum. Hamlet comes back and makes Horatio and Marcellus swear that they won’t say a word on this.