Instinct
(1999)

Theo (Cuba Gooding Jr.) makes life at the institution easier for inmates by giving them privileges easier (such as going outside) and presses charges against security officer Dacks (John Ashton) for abusing all the inmates.

Meanwhile, Ethan explains in sessions how he came to be accepted by the gorillas he was studying in Africa, but they were all killed or captured by poachers one day, which persuaded Ethan to kill the poachers. Theo takes Ethan to a gorilla reserve to show Ethan one of the gorillas that was rescued from Africa. Ethan opens cage knowing that the gorilla will not run, explaining that the gorilla knows that freedom is only a dream. Theo explains to Ethan that he is wrong, that freedom isn't something you dream, that it is very real. Ethan seems unmoved, and becomes slightly catatonic in his behavior afterwards, but we see him using a pen to slowly chip away the brick surrounding a window fixture so that he can escape, with the help of a distraction made by inmates.

Theo comes to the institution and finds a letter written by Ethan telling him that he was right about freedom, and he knows that no one will ever find Ethan, who we are led to believe has gone back to Africa to be with his primate family.

Thanks Herbmeistr!