One of the biggest surprises in You Can See Everything, the new documentary about Elizabeth Holmes, is being protected by a pact of silence. Directors Nathan Fielder and Lance Oppenheim asked critics who attended the secret Telluride Film Festival screening not to reveal the identity of a famous actress who appears in the film.

All we know is that she agreed to meet Fielder, became fascinated by what was happening, and eventually joined the production. Her apparently accidental participation grew until she became a collaborator: She appears as herself, comments on the insanity of the situation, and also plays Holmes in the reenactments.

One critic described her arrival as “the craziest twist in an already crazy film.” But who could she be?

Amanda Seyfried Is the Strongest Possibility

My money is on Amanda Seyfried. She won an Emmy for playing Holmes in The Dropout and became almost inseparable from the fictional version of the Theranos founder.

Her casting would create an irresistibly meta structure. Elizabeth Holmes plays herself in front of the cameras. Amanda plays Elizabeth in the reenactments. Nathan observes them both and tries to determine whether a real personality exists beneath so many layers of performance.

There is another significant clue: Holmes watches scenes from The Dropout in the documentary. She becomes irritated by a sequence in which the Theranos machine breaks down in front of the employees and is visibly shaken when fiction forces her to revisit her relationship with Sunny Balwani. If Amanda then appears to recreate Holmes’ version of events, Fielder will have constructed a perfect hall of mirrors.

Jennifer Lawrence Would Be a Delicious Irony

The second possibility is Jennifer Lawrence, who was once attached to play Holmes in Bad Blood, Adam McKay’s planned Theranos film.

Lawrence left the project after watching The Dropout. According to her, Amanda Seyfried had already played the role perfectly, leaving no reason to attempt it again. Convincing Lawrence to finally portray Holmes inside a documentary that questions the very idea of representation would be a brilliant twist.

What If It Is Emma Stone?

Emma Stone also makes sense. She worked with Fielder on The Curse, understands his process, and was at the Telluride Film Festival when You Can See Everything was unveiled.

Stone seems exactly like someone who would agree to a conversation, become fascinated by the experiment, and eventually participate in it creatively. The problem is that, because of her previous connection to Fielder, her presence would be surprising but perhaps not as jaw-dropping as critics have suggested.

Kate McKinnon Completes the List

Kate McKinnon was the first actress announced to play Holmes in The Dropout, but she left the project before filming and was replaced by Amanda Seyfried. Bringing her back now would be another way of playing with the version of the story that might have existed.

It is a less likely theory, although perfectly suited to Fielder’s world: An actress would play the character she was once supposed to portray in a television series but never did.

The Surprise That May Explain the Film

For now, no one has broken the agreement and revealed the actress’ identity. The secrecy, however, confirms that this is not a decorative cameo. She apparently changes the shape of the documentary and helps Fielder understand — or attempt to understand — Elizabeth Holmes.

Amanda Seyfried remains the most logical bet. And precisely because she seems so logical, perhaps Nathan Fielder has prepared something even stranger. With him, whenever we think we have finally understood the experiment, we have probably already become part of it.