What incident serves to initiate the falling action in hamlet?

The incident was as follows:

Hamlet does not know whether the spirit of his father told him the truth about Claudius having killed him, but the arrival of an artistic troupe in Elsinore is a solution to the doubt. He will set up a play, staging the murder of his father - as the ghost told him - and determine, with Horacio's help, the guilt or innocence of Claudius, studying his reaction. The whole court is summoned to watch the spectacle; Hamlet provides commentary throughout the performance. When the scene of the murder is performed, Claudius, "very pale, stands staggering," which Hamlet interprets as proof of his guilt. Claudio, fearing for his own life, banished Hamlet to England on a pretext, watched over by Rosencrantz and Guildenstern, with a letter telling the bearer to be killed.

a. it reminds protestors of the reasons they have to protest.

could you give the story