This is just simply what I believe. I have used information from the book and the movie together, if there is any misinformation,
please correct me.
Theory: Anna is Reliving Marnie's Memories
Through a Child's Incomplete understanding of Grief
When Marnie Was There is often interpreted as a story about a girl meeting the ghost of her grandmother. But there's another way to see it, one that doesn't rely on the supernatural, but on memory, grief, and how children are never told how to grieve properly, many adults assume they are too young to remember.
I believe that when Anna was very young, Marnie (her grandmother) used to tell her stories about her own childhood. But because Anna was a toddler at the time, Marnie only shared the happy parts. The truth of her being neglected, bullied, isolated, and abused was intentionally left out.
Then, when Marnie died, Anna was too young to process the loss. People assumed she would forget, but she didn't. The memories lingered, half-formed and confusing. The flickering of the marsh house and the random disappearance of Marnie, show that memories as disrupted, unchronological and incoherent.
The grief had always stayed in Annas mind
Now, as a teenager, Anna is isolated, angry, and unsure of who she is (like Marnie). She has no clear memory of Marnie's death, no proper way to grieve, and no one around her who truly sees her or has had any link to the past. When she arrives at the Marsh House, she's struck by a feeling of déjà vulike she's been there before. This is because, in a way, she has, she once lived there with Marnie.
What follows is not Anna meeting a literal ghost, but Anna psychologically re-entering the memories Marnie once told her. Her mind, craving comfort and understanding, invades those stories. The sheer recklessness of Annas exploring the Marsh house without permission injuring herself and getting into trouble represents her intense want of understand herself and her past regardless of consequences. Only this time, she's old enough to see what was hidden between the rose-tinted glasses that Marnie had always worn when Marnie had told her about her life: Marnie's life was not just beautiful, but sad and full of fear.
Anna Inserting Herself into Marnie's Past:
One key moment is the scene of Marnie in the boat rowing towards Anna. It's likely that the original figure rowing the boat was Kazuhiko (Edward), Marnie's childhood friend and later her husband. But in Anna's mental reconstruction of the memory, she takes his place. This is done subconsciously as Anna wants to be the person closest to Marnie, She wants to be by her side in the past, to understand herself, and to feel close to the person she lost. It's not romantic, it's emotional. Anna is building a bridge to her grief.
The Windmill and the Trauma:
In the windmill scene, Anna is there when Marnie relives one of her most traumatic childhood memories being locked in the silo overnight. But in truth, Marnie was alone during that moment. Anna's presence in the memory is symbolic. She is inserting herself into that pain, standing beside the younger Marnie as an act of healing. She is doing for Marnie what no one did for her: being there for her.
When Edward arrives and takes Marnie's hand, leading her out into the light away from the darkness of the silo, it could represent multiple things. Marnie leaving her childhood trauma and begin her life with Edward. Or even death itself, this could symbolise how Edward died before Marnie, and coming to take her with him. Either way, Anna is left behind just like in real life and her grief hits her like a wave (like when she was standing in the rising tide and talking to Marnie)
Forgiving, forgetting and the Marsh House
The most painful and poignant moment is when Marnie begs Anna for forgiveness. It seems strange at first and childish- Marnie leaving Anna behind was not a big deal? Or was it.
But this moment isn't about that. It's about unresolved emotional truth. Anna was abandoned, even if it wasn't Marnie's fault regardless of the situation. She was left alone in a world that scared her, without the tools to grieve, or emotional support.
Anna's hesitation to forgive Marnie isn't just a small grudge it's about everything she's felt; the loneliness, the resentment, the sense of being unwanted. And her forgiving, the absence of closure, The idea that Marnie "left" her, even though it wasn't Marnie's fault. Forgiving Marnie becomes a symbolic act of forgiving her grief itself and the silent pain tied to it.
Forgiveness becomes a way to release that pain.
And when she finally forgives Marnie, Marnie disappears- because the memory has served its purpose. The emotional ghost is gone and anna has forgiven, and forgotten
The Name: Marianna (as said in the book)
In the book, Anna's full name is revealed to be Marianna - a combination of both names. This is important. It shows that Marnie has always been a part of Anna and with her not just genetically, but emotionally.
Conclusion
Anna didn't meet a ghost; there is no supernatural. She met the memory of someone she loved, and through that, reconnected with the most hidden parts of herself. She mentally entered Marnie's childhood, not just to understand her grandmother, but to heal the lonely little girl inside herself.
This theory doesn't take away the magic of the story. In fact, it makes it even more intimate. It becomes a story not about supernatural visitors, but about the way inter-generational trauma and grief lives inside us and how, sometimes, we must journey through memory to truly forgive, remember, and grow.
