Hamlet devises a plan to test the Ghost's words after the players arrive at the castle. His plan is to have them play out a scene that is surprisingly identical to that which the Ghost described of Claudius. If Claudius gets nervous in any way, Hamlet would know that it was true. Here is the original thought as it struck Hamlet:
With most miraculous organ, I'll have these players
Play something like the murder of my father(590)
Before mine uncle. I'll observe his looks;
I'll tent him to the quick. If he but blench,
I know my course... The play's the thing
Wherein I'll catch the conscience of the King.
This thought was born in the end of Act II, scene ii.
By Act III, scene ii, the play as Hamlet authored was underway. Hamlet sat with his mother and made a mockery of the play acting as if it was a great work based on another play by someone else. After suggestions of the killing of the original king, King Claudius arises, has the lights turned on, and he leaves the play altogether. Hamlet feels that he reached his desired effect and says so in these words to Horatio:
O good Horatio, I'll take the ghost's word for a(275)