missed the ending due to power failure

Ellen breaks out of the institution and sneaks into the family home. She approaches Gregory from behind with a gun and confronts him with the fact that his crinkled match is like the one she saw left at Lucian Randall's place. It's the clue that triggered Ellen's memory of the shooting. Gregory reveals that he plotted to punish Ellen in revenge for her father passing a judgement that put him away for 4 years in a mental asylum. He was released after proving his sanity, but he was secretly unhappy with Ellen's father for thinking it would be enough to simply apologize and give him a job in his office. Gregory's plan won't be complete without Ellen killing him and then being sent away to experience the same mental torture that he had to suffer. Ellen refuses to shoot and Gregory chases her to the attic where David comes to her aid. Reaching for Ellen's gun, Gregory knocks the support beam loose from the oversized mirror that Ellen bumped into at the beginning of the movie and it crashes down on him, killing him. The End.