Underwater near the Monterey Submarine Canyon, Jay observes the massive sperm whale. The sight fills him with awe and reminds him of his father’s reverence for the species. He imagines the respect that he will finally earn from the diving community when he reports this encounter.

As Jay makes eye contact with the whale, he is overcome by a sense of a shared, intelligent consciousness. In the whale’s gaze, he perceives the presence of a sentient soul.

A flashback to 2018 details Mitt’s failed whale-watching business. Broke, he buys a boat named Sleep, which is entirely unfit for the sea. Jay helps him to prepare the vessel and to distribute advertisements, and Mitt wryly reflects that his authentic appearance as a “salty” dog initially helps them to attract customers.

While Jay serves the passengers, Mitt manages the boat and lectures his son, explaining that customers are truly seeking a feeling of awe. Mitt complains that experiences like whale-watching have become a commodity.

In the present, Jay examines the sperm whale’s body and sees that it is covered in scars from past battles and collisions with boat propellers. The sight of the whale’s scarred hide triggers a memory of his father’s own numerous scars.

Jay recalls various facts that Mitt taught him about sperm whales and finds himself comparing the old, battle-worn animal to his father. Although Jay has not found Mitt’s body, he feels a deep connection with the whale, imagining it as a living tomb for his father’s remains.

The giant squid suddenly reacts to the whale’s arrival, bringing Jay’s attention back to it. Jay notices sucker marks on the whale’s head and realizes that the whale is hunting the squid; this explains the squid’s uncharacteristic rise from the depths. Panicked, Jay tries to escape toward a nearby cliff face but misjudges a handhold and tumbles downward into the underwater canyon.

As the squid’s body flares brightly with bioluminescence, the whale emits a powerful echolocational click, a sharp “TAK” sound that stuns Jay with the sheer force of this sonic concussion. He recognizes the sound as one that his father used to listen for on his hydrophone and realizes the whale is echolocating.

As Jay is hit by the whale’s repeated, painful clicks, he remembers his father teaching him that sperm whale clicks are the loudest sound produced by any animal in the world. Mitt once told him a story about a diver who was paralyzed by the clicks of a whale calf; his father also gleefully suggested that an adult’s clicks could be powerful enough to break bones.

As the giant squid is pulled backward toward the whale, Jay realizes that an invisible suction force has caught hold of him as well. As he struggles, the whale opens its massive jaw, revealing rows of sharp, conical teeth.

Jay is sucked into the whale’s mouth along with the squid. The squid fights back, latching onto the whale’s head. During the struggle, Jay’s left scuba fin hits the whale and breaks off, sending a jolt of pain up his leg. Sliding feet-first into the whale’s mouth, he desperately tries to grab the slick teeth and pull himself out, but he fails.

In another desperate attempt to escape, Jay inflates his BCD and jettisons his weight pouches and the D batteries. He rises quickly and pushes off the roof of the whale’s mouth, escaping its maw. As he finds himself free, he gleefully thinks of the story that he will tell his family and the “dive bros” about this encounter. However, he is violently jerked backward and scrapes his body against the whale’s barnacle-covered nose. He notices that one of the squid’s tentacles is tangled in his bone bag, thwarting his escape.

Jay fumbles with the bone bag’s suicide clip, but it is stuck. As the whale swallows the giant squid, the entangled tentacle drags Jay back into the closing mouth. A tooth rips a large gash in his BCD, and as his blood clouds the water, Jay fears that he has been gutted.

Cold seawater floods into Jay’s suit as the whale’s suction intensifies. He attempts to hold onto the whale’s palate, but its tongue breaks his grip. For a moment, his air tank gets jammed in the whale’s throat, and he sees two inexplicable, trident-like symbols etched in roof of the whale’s mouth, just over the cavern of the throat. The throat then stretches wide, pulling him into darkness.

After being swallowed, Jay experiences a moment of sensory transition and perceives his dark, enclosed environment as an entire universe.

The narrative shifts back in time to the period when Jay’s family repeatedly pleads with him to visit his dying father. He compares their indirect communication to echolocation—a series of clicks calling him home. Mitt ultimately dies by suicide, and his body is never recovered.

Eleven months after his father’s death, Jay confronts Hewey, who admits to misleading the Coast Guard about where Mitt took his own life. Before revealing the true coordinates, Hewey imparts a lesson from the Qur’an, telling Jay that “truth never outweighs mercy” (111).

In a series of brief moments consisting of one line per chapter, a disembodied voice repeatedly asks Jay where he is. The question echoes four times, with each repetition growing in intensity until the final inquiry becomes a desperate shout.

In a flashback to 2020, a drunken Mitt rants aboard his boat, the Sleep, after his whale-watching business has failed. (Two customers fell into the water due to a faulty railing on the Sleep, and when they filed complaints, Mitt’s license was suspended.) Now completely inebriated, Mitt smashes beer cans on his head, creating gashes and smearing the blood across his face. Blood permeates his saliva as well—evidence of the as-yet-undiagnosed mesothelioma. As Mitt rants about the modern world’s failure to respect whales and romanticizes the idea of Indigenous hunters and shamans who did, an increasingly fearful Jay reflects that there are no “right answers” to his father’s agitated words. Expounding on the importance of tattoos as a rite of passage, Mitt hands Jay a torn beer tab and urges Jay to cut himself with it. When Jay refuses, he offers a knife instead.

As the blade is held out, the boat rocks, and Jay perceives the sudden motion as an attack. He kicks his father away and orders Mitt to stay away from him, reflecting that it has taken him 15 years to say this. As Mitt drunkenly and nonsensically rambles about an idealized image of whale-hunting and urges Jay to “pray” with him, he creates a brief opportunity for reconciliation. However, he then taunts Jay about his soft lungs, ruining the moment. Infuriated, Jay accuses Mitt of abdicating his responsibilities as a father and jumps overboard, leaving his father for good. As he does, he catches his father’s assertion that sons also have responsibilities.

In the present, Jay regains consciousness to find himself inside a dark, warm, tight space: the whale’s first stomach chamber. A peristaltic wave constricts around him, and he recalls that sperm whales “chew” with their stomachs. So far, his dive tank is the only thing that has saved him from being crushed. His memory of being swallowed returns, and he keenly feels the impossibility of his predicament.

As Jay assesses his situation, he discovers he is not alone. The squid has also survived. It coils an arm around his neck and squeezes.

The squid’s suckers slice open Jay’s neoprene hood as all ten appendages encircle him.

When the whale’s stomach contracts again, the immense pressure kills the squid. Its remains are flushed deeper into the whale. Realizing that he is hyperventilating, Jay removes his mask to get more air but gags on the foul stench and vomits into his regulator. He purges the mess, but not before inhaling stomach acid that burns his lungs. Overwhelmed by pain, Jay gives up and resigns himself to death.

The disembodied voice returns, once again asking Jay where he is. Jay answers that he is alone. The voice then commands him to open his eyes. Dismissing the voice as a hallucination, Jay instead focuses on the whale’s heartbeat. When the command is repeated, Jay obeys and is shocked to discover that he can see in the darkness.

Jay sees that the stomach walls are illuminated by a faint light. The voice asks him, “What do we eat” (126), and Jay realizes that the light comes from the squid’s bioluminescent residue. Jay can also see that other small, glowing deep-sea creatures are still alive in the stomach with him.

The voice asks Jay what “What are we” (128). Jay decides to move toward the channel where the dead squid disappeared. To make crawling easier, he removes his remaining fin. Ignoring the voice’s repeated warning of ”Don’t,” he forces his way through a sphincter and into the next chamber.

Jay enters a second stomach chamber and finds it to be much hotter and dangerously acidic. The voice yells at him, “GO BACK,” and Jay realizes that he is in the whale’s main digestive stomach. The acid is burning his exposed skin, cooking him alive.

While crawling through the sludge, Jay impales his right palm on a sharp object. He discovers that it is an indigestible giant squid beak: one of many in this chamber. The pain is too severe for him to remove the sharp object, so he leaves it embedded in his hand.

Jay discovers that the passage to the whale’s third stomach is a tube that is far too small for him to fit through. With all hope lost, he removes his regulator, intending to give up and die. The disembodied voice commands him to “PUT IT BACK” (135), then shouts his name. Stunned, Jay hesitates.

The voice speaks to Jay again. As Jay surveys his own burned and wounded hands, he is reminded of his father’s scars. He also recognizes that the voice’s tone is Mitt’s as well, so he accepts the idea that the voice is either his father, the whale, or evidence of his own eroding sanity.

Jay argues with his father’s voice, which berates him for his weakness. Jay resists until the voice commands him to “remember the bad air” (137).

The voice triggers a flashback to 2015, when a 10-year-old Jay accompanies Mitt on a job at a landfill. The owner warns them of “bad air,” rising from a lagoon but does not specify that this bad air is actually methane gas, which is very dangerous. Mitt dives into the lagoon to retrieve a drill bit but stays underwater too long. When he finally resurfaces, he is disoriented and struggling to breathe, still overcome by methane fumes. The owner is unapologetic, and Mitt refuses to continue with the job.

Jay’s memory of his father’s mishap clarifies the immediate danger: The whale’s stomach is filled with poisonous methane. Spurred by Mitt’s voice shouting “MOVE,” Jay puts his regulator back in, purges it, and breathes clean air, feeling his head clear. He then turns his body around in an attempt to retreat back to the first chamber.

Jay struggles back through the sphincter and reenters the first chamber, only for another contraction to crush him against his tank. Mitt’s voice tells him, “Everything you need you brought with you” (143) and commands him to “REACH OUT.” Following the order, Jay stretches out his hand and touches the scuba fin that he left behind.

Jay wedges the fin against the stomach wall, creating a brace that lessens the crushing force of the next contraction. His focus shifts to his dwindling air supply, and he finds his instrument console so that he can check the gauge.

The gauge reads a low 1720 PSI. Jay knows that he will have little time left at this rate; he must slow his breathing in order to conserve air. He recalls that the first rule of scuba diving is to never hold one’s breath, as doing so can cause a fatal embolism.

As Jay panics, his tank pressure falls. He fears that the whale might dive deeper, which would make any pressure change lethal. As his thoughts spiral, Mitt’s voice gives him a specific instruction to “breathe sleepy,” and the phrase triggers another memory.

In a flashback, a nine-year-old Jay is hyperventilating in bed, deeply distressed over the thought of failing in school. His mother asks Mitt to help. Mitt enters and gently coaches his son through a breathing exercise that he calls “breathing sleepy.” As Jay’s breathing slows and becomes more regular, he sees a rare look of pride on his father’s face.

In the present, Jay puts his father’s lesson into practice. Listening to the whale’s heartbeat and lungs, he synchronizes his breathing to their rhythm. By “breathing sleepy,” he calms himself, conserves his air, and achieves the clarity to plan his next move. He then smells mammal blood.

Tracing the source of the smell, Jay discovers a deep, bleeding wound on his neck, where the squid’s suckers sliced through his hood. He realizes that adrenaline has been masking the pain of a life-threatening injury. He searches through the debris for something to use as a bandage but finds only useless items.

Jay remembers a mandatory beach cleanup during which his father abandoned him, leaving him to collect trash with Hewey. At that time, Hewey explained that many whales die from ingesting plastic trash. Hewey philosophized that while all creatures are fish food in the cycle of life, plastic disrupts this natural order.

In the present, Jay decides to cut a piece of his neoprene hood away to use it as a bandage, but he laments his lack of a knife. In frustration, he slams his injured hand into the mire and feels a sharp pain from the squid beak that is still embedded in his palm. He suddenly realizes that he already has a cutting tool.

Jay endures excruciating pain as he pulls the squid beak from his palm, tearing out a wedge of flesh. He separates the beak’s two mandibles and keeps the sharper upper mandible. Gripping the makeshift tool, he begins to saw at the thick neoprene of his hood even as the beak slices more deeply into his hand.