Shutter Island Ending Explained: Scorsese's Psychological Thriller Delivers A Masterful Twist

If you saw "Shutter Island" in the theater back in February 2010, you may have come away feeling like you had just watched the first great movie of the new decade ... or you may have been disappointed. Or perhaps you were simply left confused by the movie's third-act plot twists and ending.

People coming to "Shutter Island" on streaming services or digital platforms in the 2020s will have their own range of emotions. This film marked the fourth collaboration between director Martin Scorsese and his go-to leading man for the 21st century, Leonardo DiCaprio. It was and is an atmospheric genre exercise, not unlike the one that Scorsese and his other go-to star, Robert De Niro, performed with their 1991 remake of "Cape Fear."

"Shutter Island" explores the psychological thriller through the lens of Catholic guilt. You don't have to be Catholic to experience guilt, of course, but that's the perspective that Scorsese, the pre-seminary dropout, has brought to many of his films.

Most people, when they sit down to watch "Shutter Island," are just going to be focused on the superficial plot maneuverings. On a repeat viewing, however, it's easier to see where plot is almost reverse-engineered from Theme in Scorsese's film. Plot becomes a series of hoops that the viewer has to jump through with DiCaprio's character, Teddy, who flashes his badge and describes himself, in his Boston accent and '50s period attire, as a "duly appointed federal marshal."

Does the ending of "Shutter Island" hold up on a repeat viewing, or even a first viewing? Let's look at it — with spoilers, of course.

The Walls of Ashecliffe

Here's the thing about "Shutter Island." The whole movie is basically one of those murder mystery party games, conducted as a form of therapy to help a guilt-ridden mental patient work through his issues and embrace who he is and what he has done. In this case, the murderer doesn't know he's a murderer. He's on a voyage of self-discovery, so to speak.

It begins on a ferry, which cuts through the mist, blowing its foghorn en route to the island, where Teddy will begin his investigation at the Ashecliffe Hospital ... "for the criminally insane." Krzysztof Penderecki's "Symphony No. 3: Passacaglia" lays the mood on, musically, and the sight of the island under gloomy grey skies, across the water, is foreboding.

Right from the start, things are off. Why is Teddy just now meeting his new partner, Chuck, played by Mark Ruffalo, for the first time on the ship's deck? When they get to the island, why are the guards so on edge? Why does Chuck have so much trouble extracting his gun holster from his belt when they surrender their weapons to the Deputy Warden (John Carroll Lynch)? Questions like these add up and are ultimately answered by the film's twist ending. 

No one in the hospital seems to take Teddy, this supposed federal agent, very seriously. His investigation is stonewalled at every turn. He initially believes he's there to solve the disappearance of a patient named Rachel Solondo — a locked-room mystery. Dr. Cawley (Ben Kingsley) tells Teddy, "It's as if she evaporated straight through the walls."

A Rat in a Maze

Dr. Cawley is an important figure in "Shutter Island," as is Chuck. Kingsley and Ruffalo both imbue their performances with little nuances that read differently on a rewatch. Once you know the movie's ending and have it in mind, you're liable to perceive certain things differently.

Note how Dr. Cawley shoots Teddy a meaningful glance when he talks about Rachel drowning her children. He's also quick to correct Teddy, stressing that Rachel is a patient, not a prisoner. The problem is, Rachel Solondo doesn't exist, and Teddy himself is both a patient and a prisoner of his own guilt and trauma. It just takes him the better part of 137 minutes to realize it.

While he figures things out, "Shutter Island" puts the viewer in his paranoid shoes. Teddy is the protagonist — the audience surrogate. He believes he's at the center of a conspiracy, and in a way, he is, since the hospital staff is conspiring to go along with his delusions.

Only his old friend, George Noyce (Jackie Earle Haley), is straight with him. George tells Teddy he's "a rat in a maze," that this is all a game for him. He's running around, obsessing over cryptic notes ("The law of 4; who is 67?") and having fireside conversations in caves with women who aren't real.

We meet two different Rachels; Emily Mortimer plays one and Patricia Clarkson plays the other. Yet Teddy also reveals that he has an ulterior motive for visiting Shutter Island. He wants to find Andrew Laeddis, the arsonist who set the fire that killed his wife. He talks the plot with Chuck and has visions of Laeddis (Elias Koteas), but we never see this character in waking reality until the end, when Teddy realizes that he is Laeddis.

To the Lighthouse

All along the way, "Shutter Island" drops hints that something is not right with this picture. It gives you these clues, like the disappearing water glass, which is there in the woman's hand in one frame, but gone the next.

When Teddy finally makes it to the lighthouse in the third act, Dr. Cawley is there waiting for him. The lighthouse, per its function, is a place that will illuminate Teddy's true identity and the true nature of this mystery. It confronts Teddy with self-knowledge. Chuck shows up, back from the dead, and it turns out he is really the MIA Dr. Sheehan, Teddy's primary psychiatrist.

Dr. Cawley even whips out visual aids (a chart with anagrams, a transcript of Teddy's conversation with George) in an effort to make Teddy see the truth about himself. The truth is, Teddy/Andrew killed his wife, Dolores (Michelle Williams), after she had a psychotic break and drowned their three children. This is revealed in a flashback, where DiCaprio does some serious emoting through the character's anguished cries as he fishes his children out of the lake.

Dolores told Teddy/Andrew that she had "an insect living inside her brain, clicking across her skull." There were warning signs that she was mentally unstable, but he didn't see it until it was too late. His children were dead, and his grief drove him to shoot his wife.

Andrew Laeddis couldn't live with the guilt of what he had done (and what he hadn't done), so his mind retreated into what his patient chart calls "highly developed and fantastical narratives." The mystery of Rachel and the scarred arsonist, Laeddis — Andrew's whole persona as Teddy — are part of that.

"To Live as a Monster, or Die as a Good Man"

At one point in "Shutter Island," Teddy has an encounter with Dr. Naehring (Max von Sydow) in the bowels of the hospital. Dr. Naehring talks about how the word "trauma" came from the Greek word for "wound," saying:

"Wounds can create monsters. And you, you are wounded, marshal. Wouldn't you agree? When you see a monster, you must stop it."

By the end, Teddy has come around to this way of thinking. He knows he's wounded and that he's a monster prone to violent outbursts, who has hurt other people, not just his wife. The 67th patient at Ashecliffe is him. If the doctors can't break through to him and get him to accept the reality of his situation, "Permanent measures will be taken to ensure he can never hurt anyone again." He'll be lobotomized. 

Teddy's hallucinations of Dolores have already warned him that the lighthouse will be the end of him. Dr. Cawley explains that everyone humored Andrew's mock investigation as part of "the most radical, cutting-edge roleplay ever attempted in psychiatry."

Teddy finally has a moment of clarity and he says it out loud: "My name is Andrew Laeddis, and I murdered my wife in the spring of '52." He appears to have recovered, but at the very end he feigns being delusional again, knowing that it will get him lobotomized. Teddy/Andrew's decision is explained by his final line of dialogue, when he asks Chuck/Dr. Sheeran, "Which would be worse — to live as a monster, or to die as a good man?"

"Shutter Island" leaves that question hanging in the air as Andrew goes to meet his doom.

The Thriller as Guilt Parable

"Shutter Island" has a reputation for being one of Scorsese's lesser films. It's one of those twisty thrillers like "The Usual Suspects" where the ending rejiggers much of what you've seen. Some viewers might not be on board with the film's denouement, but if you approach it from thematic standpoint, this is an underrated movie with some deep resonance to it.

Most people probably have something in their lives they regret, something they wish they could go back and do or undo. We don't all "create an elaborate fictional structure" to process grief and guilt, as Andrew Laeddis does and as artists sometimes do. But if you're hooked into the themes and believe that art can function as therapy, Andrew's story is one with some real catharsis to it. Denis Villeneuve later used the same grief-laden piece of music, Max Richter's "On the Nature of Daylight," in his Oscar-winning film "Arrival."

Not everything in "Shutter Island" holds up. On the way to its twist ending the film flounders a bit in its second act, getting lost in the maze it has devised for Teddy and us. It could have probably stood to shave off some of those extra 17 minutes and be closer to a traditional two-hour feature.

The way Chuck goes along with some things — even putting ideas in Teddy's head and nourishing his delusions — doesn't always make sense, retroactively, if he's a psychiatrist trying to nurture him back to health. Then again, the line where Teddy's hallucinations begin and end isn't always clear.

There's a scene with Ted Levine in a jeep, where he talks about violence conquering violence and how "God loves violence." It's a great scene, and memorable enough to justify its inclusion; but in the context of an already protracted running time, it feels narratively extraneous, like it's going off in the direction of a different theme that belongs to a different Scorsese film (one with gangsters, probably).

That's not to say that a movie like this can't have more than one theme or interpretation. But if you're willing to wade into the deep end of the pool (or drowning lake), "Shutter Island" is a film where trauma, grief, guilt, and regret meet in a tempest of raw emotion — the kind that can only be channeled through a hearty Leonardo DiCaprio outburst.