Nemuri no Mori

A man is found dead in an office of the Takayanagi Ballet Company. The suspect, who a dancer in the company, is found lying down unconscious in the same room. According to the suspect, the man was a robber who had tried to attack her. She insists that in self-defence, she hit him on the head and killed him. After a series of investigations, suspicions surrounding her clam begins to surface. Later on, the director of the Takayanagi Ballet Company is poisoned to death. Are the cases related?