The Killing is adding Oscar-nominated actress Joan Allen to the cast of its six-episode fourth and final season on Netflix. The new installment will follow a new murder investigation led by homicide detectives Sarah Linden (Mireille Enos) and Stephen Holder (Joel Kinnaman). In a major recurring role, Allen will play Margaret O’Neal, the head of an all-boys military academy based outside of Seattle. Fox TV Studios is producing. ICM Partners-repped Allen was recently seen in the latest installment from the Bourne movie franchise and on HBO drama Luck.