The first time we see Gypsy Rose Blanchard–the subject of Erin Lee Carr’s fascinating new HBO documentary Mommy Dead and Dearest–she’s in a police interrogation room. Meek, high-voiced and nearly bald, she tries to feign shock when a detective mentions her dead mother Dee Dee Blanchard, as though she’s hearing the news for the first time.

Minutes later, Carr shows us Blanchard again, and a transformation has taken place. She has the same high voice, but in the intervening months she’s grown a full head of hair and, it seems, a new sense of maturity and self-assuredness. It’s here that she makes an admission which in many ways comes to define the scope of Carr’s film.

“This is actually kinda the first time I’ve been honest,“ she says.

Though it features the same intermingling of talking head interviews and home video footage that devotees of the genre will recognize, Mommy Dead and Dearest is not a typical true crime documentary. Who committed the crimes at hand is not in question. Neither is why, at least on a level of assigning a basic motive. Let’s start at the beginning: Dee Dee Blanchard and her daughter Gypsy Rose were inseparable, partially because Gypsy was wheelchair-bound and suffered a litany of diseases. That was until the murder.

Dee Dee Blanchard was, the film tells us, stabbed to death by her daughter’s boyfriend Nicholas Godejohn in her Missouri home in June 2015. Godejohn apparenty committed the crime at the urging of Gypsy Rose so they could run away together after Gypsy suffered years of abuse at the hands of her mother. Those details, plus graphic Facebook updates posted to Gypsy’s account after the murder and a secret online relationship she had with Godejohn, were lurid enough to grab national headlines. As journalist Michelle Dean (who reported extensively on the Blanchard case) notes in the film, the crime had all the makings of a front page tabloid story. Then, things got very strange.

Director Carr fixates on the strange events surrounding the actual murder, allowing them to drive her film. The title refers to the mother. Indeed, Dee Dee Blanchard hovers over Mommy Dead and Dearest like a ghost. The film itself, though, is the story of a daughter whose entire existence is built on lies and whose life is ultimately warped perhaps beyond repair not by her own demons but her mother’s.

After the crime and subsequent capture of both Gypsy Rose and Godejohn, something became very clear very quickly: the Blanchards were not the inseparable duo they appeared to be. To everyone who knew them, they appeared as a sickly but hopeful child and a loving mother with a God-given calling to be her daughter’s constant caregiver. This image got them fundraisers, local news appearances and even a Habitat for Humanity home.

But Gypsy was not, as her mother claimed, wheelchair bound due to muscular dystrophy. She was not bald because she suffered from leukemia. She did not require the feeding tube doctors implanted or the dozens of medications she was prescribed, some of which wound up causing the symptoms they were meant to treat. She was instead a pawn in a years-long scheme spurred on by Munchausen by proxy syndrome, a psychological condition that drove her mother to insist her daughter had these many illnesses in a bid for attention and praise.

The conditon itself is fascinating, as is Dee Dee’s apparent lifelong association with schemes and lies (she apparently tried to poison a family member at one point). While Carr certainly lingers there, though, the real meat of the film–and much of its emotional power–comes from Gypsy Rose and her strange relationship with her mother and her illness.

Gypsy Rose is a victim, to be sure, but she also spent years as a participant in her mother’s lies. She fell under the spell of her boyfriend’s often-dark online life, but she also allowed him to enter her home and murder her mother (she claims she hid in the bathroom when the crime took place). She expresses both love for her mother and an earnest desire to end her own suffering even if it means murder. She is obviously the product of an extremely sheltered upbringing, yet she’s articulate, charming and even possesses some kind of dark side of her own. How deep that dark side goes is unclear.

Carr’s film is at its most compelling and intellectually propulsive when it prods at these contradictions, juxtaposing them in an effort to understand how Gypsy became who she is now. Though it was never clear to her exactly where the lies ended and the truth began, she always knew she wasn’t wheelchair bound. She also eventually knew that her closely guarded existence was not normal. This slow emotional discovery of her mother’s lies is gut-wrenching in and of itself but it ultimately raises a deeper question. What does it do to your psyche when your entire life is the product of a deception, even if you didn’t start it? When you realize the depth of the lie you’re living, do you even know how to live honestly? Where would you even start?

Mommy Dead and Dearest asks these questions for 90 compelling minutes. It refracts them through Gypsy Rose herself but also through public perception, social media and the guilt that comes from knowing you somehow unwittingly enabled such a scheme. Through those questions and the myriad ways in which they’re explored, Gypsy herself becomes a fascinating knot of mystery, perplexing even in her most earnest attempts at the truth.

If there’s a major flaw in the film, it’s that it raises more questions than its runtime can possibly contain. There are themes dangling like loose threads everywhere, from the role of the internet in the story to the wider psychological community’s view of Munchausen by proxy to the ways in which the medical and social services systems failed to catch Dee Dee’s deceptions. You keep waiting for the film to follow the string into some deeper revelation. As the credits roll, you’re still waiting. Ultimately, it feels more like a limitation of the format than a shortcoming of the filmmakers.

Mommy Dead and Dearest may confound and frustrate even as it grips you. It may leave you running to Google in a search for answers it doesn’t provide. You may not find what you’re looking for but that sense of infectious curiosity is perhaps the greatest testament to the film’s power. This documentary will embed itself in your brain and stay there all week.

Mommy Dead and Dearest premieres Monday at 10 p.m. ET/PT on HBO.