Though Kevin has evidenced 23 personalities to his trusted psychiatrist, Dr. Fletcher, there remains one still submerged who is set to materialize and dominate all of the others. Compelled to abduct three teenage girls led by the willful, observant Casey, Kevin reaches a war for survival among all of those contained within him -- as well as everyone around him -- as the walls between his compartments shatter.
Principal photography on the film began on November 11, 2015, in Philadelphia, Pennsylvania. Reshoots occurred in June 2016. During post-production, Sterling K. Brown's role as Shaw, Dr. Fletcher's neighbor, was cut from the film, as Shyamalan felt that his scenes were ultimately unnecessary. McAvoy broke his hand in a scene where he was supposed to punch a metal door, but missed the soft section of the door he intended to hit.