Image released by Focus Features. Charlize Theron in a scene from “Tully.” (Kimberly French/Focus Features via AP)

Attention: Spoilers ahead. 

“You pretty much are the baby right now,” says Tully, the night nanny (MacKenzie Davis) for whom the recently released feature film is named. Impossibly young and thin, she has a surplus of energy as she plays opposite Charlize Theron’s character Marlo, an exhausted 40-something woman who has just given birth to her third baby.

Marlo’s much more substantial postpartum frame (Theron reportedly gained 50 pounds for the role) represents bodies seldom seen on film but recognized by most women: bodies that have swollen and stretched and now sag; bodies that have a troubling tendency to leak blood and milk and other fluids; bodies that play host organism, to varying degrees, to other bodies.

As she coos over Marlo’s newborn, Tully points out that the baby’s cells are still circulating through Marlo’s body, and will do so for years, an observation that, depending on one’s frame of mind, can sound beautiful and intimately tender, or terrifying: an intrusion; a takeover. You pretty much are the baby right now. The baby has erased you.

Paradox is at the heart of motherhood, and of “Tully,” too: Is the mother an individual, or is she not? Is the woman who becomes a mother the same woman she was before, or is she different? (In a late scene, Tully points out to Marlo that virtually every cell in her body has been regenerated over the years, like a boat in which every board has been replaced. Is she, then, really the same person as she was 20 years ago? In what sense?) Is the woman whose body carries and feeds children all day the same woman who climbs astride her husband at night? Is motherhood beautiful and transcendent, or is it earthy, repulsive and terrifying? Is the mother solid or liquid, a creature of land or a creature of the water? The film explores these questions with a frankness seldom seen in the mommy-Instagram scene.

The feminist philosopher Sara Ruddick has suggested that women’s bodies, in the Western tradition, have stood for all that reason is not; for all that is opposed to rationality. Aristotle’s identity principle, upon which all rationality rests, states that A is A, and A is not non-A. So perhaps it is not the whole truth to say of a pregnant woman that she is merely herself, and not an other, or to say that she is not-herself or not-baby. There is that mother-baby enmeshment at the cellular level but also at the level of experience: What adult has not, in the full catastrophe of life with children, wondered something like where did “I” go?

“Tully” is disturbing, but not primarily because it appears to portray postpartum psychosis. That may be, though, notably, Marlo is not given a diagnosis at the film’s end. Rather, it seems that mental illness is a vehicle for pointing to this complicated perception that, through motherhood, one’s self is attenuated even as it is enlarged: You are not quite who you were, you are not quite the baby (but not quite detachable from the baby, either), and you are somehow not even quite who you are: ‘You’ will not always leak milk, blood and water, and exist in a severely sleep deprived state, but for now, you are covered in milk in various stages of digestion and stumbling about in an adult diaper in the middle of the night.

“Tully” is disturbing because of its vivid evocation of just what a difficult and trippy road motherhood can be: the kind of experience that makes nearly everyone question her sanity and fitness for the task (and let out the occasional primal yell of rage). And also question those who seem unruffled by it, perhaps because they have the financial resources to outsource those aspects of parenthood that aren’t pure sunlight and grace, like in the case of Marlo’s impossibly rich and snooty sister-in-law Elyse (Elaine Tan), whose children eat truffle mac and cheese in another part of their house under the care of a nanny with a master’s degree in child development. She and Marlo’s brother raise the idea of ‘gifting’ Marlo with a night nanny in the first place. Marlo’s husband worries that his much wealthier brother-in-law will lord it over them if they accept the offer of help, and Marlo herself flinches a little at the idea of someone else taking over what is, of course, one of the hardest aspects of newborn care.

Another paradox, then, one that is perhaps unique to the modern, Western, middle-class mother: We manifestly cannot do it all and feel damned when we cannot and damned if we need help. The twist, which I will not spoil, reveals this perfectly. We are expected not to need anyone and to be everything to everyone: educator, therapist, housekeeper, cook, lover and more, including our own helper, comforter and savior.

Children are like barnacles, Marlo says, over a stiff drink. Well, counters Tully, barnacles are obligate parasites — creatures that cannot live without a host, much like infants — and they destroy boats but are harmless to whales. Her question for Marlo: Which are you: boat or whale? Some women are consumed by motherhood, destroyed by it. The film does not flinch from this reality, or from the economic burdens, sociological patterns and cultural expectations that create conditions in which mothers might find themselves either foundering or floating.

To Tully’s question — will Marlo turn out to be more like a boat or more like a whale? — the film gives no definite answer. “Tully” is a provocation, unsettling what we think we know and bringing our deepest anxieties to the surface.

Rachel Marie Stone teaches English at The Stony Brook School in New York. She is the author, most recently, of Birthing Hope, a memoir of motherhood and anxiety. 

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More reading:

I may be a mother, but who am I? 

Your health and happiness matters as much as your baby’s

Yes, Duchess Kate looked flawless after giving birth. No, this isn’t normal.