The novel begins with a note from the author, which is an integral part of it. Unusually, the note describes entirely fictional events. It serves to establish and enforce one of the book's main themes: the relativity of truth.

Life of Pi is subdivided into three sections:

Part one

In the first section, the main character, by the name of Piscine Patel, an adult Canadian, reminisces about his childhood in India. His father owns a zoo in Pondicherry. The livelihood provides the family with a relatively affluent lifestyle and some understanding of animal psychology.

The narrator describes how he acquired his full name, Piscine Molitor Patel, as a tribute to the swimming pool in France. After hearing schoolmates tease him by transforming the first name into "Pissing", he establishes the short form of his name as "Pi" when he starts secondary school. The name, he says, pays tribute to the irrational number which is the ratio of the circumference of a circle to its diameter.

In recounting his experiences, Pi describes several other unusual situations involving proper names: two visitors to the zoo, one a devout Muslim, and the other a committed atheist, bear identical names; and a 450-pound tiger at the zoo bears the name Richard Parker as the result of a clerical error, in which human and animal names were reversed.

Pi is raised as a Hindu who practices vegetarianism. At the age of fourteen, he investigates Christianity and Islam, and decides to become an adherent of all three religions, much to his parents' dismay, saying he "just wants to love God." He tries to understand God through the lens of each religion, and comes to recognize benefits in each one.

A few years later in February 1976, during the period when Indian Prime Minister Indira Gandhi declares "The Emergency", Pi's father decides to sell the zoo and immigrate with his wife and sons to Canada.

Part two

The second part of the novel begins with Pi's family aboard the Tsimtsum, a Japanese freighter that is transporting animals from their zoo to North America. A few days out of port from Manila, the ship encounters a storm and sinks. Pi manages to escape in a small lifeboat, only to learn that the boat also holds a spotted hyena, an injured Grant's zebra, and an orangutan named Orange Juice. Much to the boy's distress, the hyena kills the zebra and then Orange Juice. A tiger has been hiding under the boat's tarpaulin: it's Richard Parker, who had boarded the lifeboat with ambivalent assistance from Pi himself some time before the hyena attack. Suddenly emerging from his hideaway, Richard Parker kills and eats the hyena.

Frightened, Pi constructs a small raft out of rescue flotation devices, tethers it to the bow of the boat and makes it his place of retirement. He begins conditioning Richard Parker to take a submissive role by using food as a positive reinforcer, and seasickness as a punishment mechanism, while using a whistle for signals. Soon, Pi asserts himself as the alpha animal, and is eventually able to share the boat with his feline companion, admitting in the end that Richard Parker is the one who helped him survive his ordeal.

Pi recounts various events while adrift in the Pacific Ocean. At his lowest point, exposure renders him blind and unable to catch fish. In a state of delirium, he talks with a marine "echo", which he initially identifies as Richard Parker having gained the ability to speak, but it turns out to be another blind castaway, a Frenchman, who boards the lifeboat with the intention of killing and eating Pi, but is eventually killed by Richard Parker.

Some time later, Pi's boat comes ashore on a floating island network of algae and inhabited by hundreds of thousands of meerkats. Soon, Pi and Richard Parker regain strength, but the boy's discovery of the carnivorous nature of the island's plant life forces him to return to the ocean.

Two hundred and twenty-seven days after the ship's sinking, the lifeboat washes onto a beach in Mexico, after which Richard Parker disappears into the nearby jungle without looking back, leaving Pi heartbroken at the abrupt farewell.

Part three

The third part of the novel describes a conversation between Pi and two officials from the Japanese Ministry of Transport, who are conducting an inquiry into the shipwreck. They meet him at the hospital in Mexico where he is recovering. Pi tells them his tale, but the officials reject it as unbelievable. Pi then offers them a second story in which he is adrift on a lifeboat not with zoo animals, but with the ship's cook, a Taiwanese sailor with a broken leg, and his own mother. The cook amputates the sailor's leg for use as fishing bait, then kills the sailor himself as well as Pi's mother for food, and soon he is killed by Pi, who dines on him.

The investigators note parallels between the two stories. They soon conclude that the hyena symbolizes the cook, the zebra the sailor, the orangutan Pi's mother, and the tiger represents Pi. Pi points out that neither story can be proven and neither explains the cause of the shipwreck, so he asks the officials which story they prefer: the one without animals or the one with animals. They eventually choose the story with the animals. Pi thanks them and says: "And so it goes with God." The investigators then leave and file a report.

Life is a story

Life of Pi, according to Yann Martel, can be summarized in three statements: "Life is a story... You can choose your story... A story with God is the better story." A recurring theme throughout the novel seems to be believability. Pi at the end of the book asks the two investigators "If you stumble at mere believability, what are you living for?" According to Gordon Houser there are two main themes of the book: "that all life is interdependent, and that we live and breathe via belief."

Growth through adversity

PBS has described Martel's story as one of "personal growth through adversity." The main character learns that "tigers are dangerous" at a young age when his father forces him to watch the zoo's Royal Bengal tiger patriarch, Mahisha, devour a live goat. Later, after he has been reduced to eking out a desperate existence on the lifeboat with the company of a fully grown tiger, Pi develops "alpha" qualities as he musters the strength, will and skills he needs to survive.

In a 2002 interview with PBS, Martel said "I was sort of looking for a story, not only with a small 's' but sort of with a capital 'S' – something that would direct my life." He spoke of being lonely and needing direction in his life, and found that writing the novel met this need.

Richard Parker and shipwreck narratives

The name of Martel's tiger, Richard Parker, was inspired by a character in Edgar Allan Poe's nautical adventure novel The Narrative of Arthur Gordon Pym of Nantucket (1838). In this book, Richard Parker is a mutineer who is stranded and eventually cannibalized on the hull of an overturned ship (and there is a dog aboard who is named Tiger). The author also had in mind another occurrence of the name, in the famous legal case R v Dudley and Stephens (1884) where a shipwreck again results in the cannibalism of a cabin boy named Richard Parker, this time in a lifeboat. A third Richard Parker drowned in the sinking of the Francis Spaight in 1846, described by author Jack London, and later the cabin boy (not Richard Parker) was cannibalized.

Having read about these events, Yann Martel thought, "So many victimized Richard Parkers had to mean something."

Moacyr Scliar

Martel has mentioned that a book review he read of Brazilian author Moacyr Scliar's 1981 novella Max and the Cats accounts in part for his novel's premise. Scliar's story describes a Jewish-German refugee crossing the Atlantic Ocean with a jaguar in his boat. Scliar said that he was perplexed that Martel "used the idea without consulting or even informing me," and indicated that he was reviewing the situation before deciding whether to take any action in response.^[23][24] After talking with Martel, Scliar elected not to pursue the matter.^[25] A dedication to Scliar "for the spark of life" appears in the author's note of Life of Pi. Literary reviews have described the similarities between Life of Pi and Max and the Cats as superficial. Reviewer Peter Yan wrote: "Reading the two books side-by-side, one realizes how inadequate bald plot summaries are in conveying the unique imaginative impact of each book,"^[26] and noted that Martel's distinctive narrative structure is not found in Scliar's novella. The themes of the books are also dissimilar, with Max and the Cats being an allegory for Nazism.^[27] In Life of Pi, 211 of 354 pages are devoted to Pi's experience in the lifeboat, compared to Max and the Cats, in which 17 of its 99 pages depict time spent in a lifeboat.^[27]

According to the reviewer Peter Yan,

'Life of Pi' is told from two alternating points of view, the main character Pi in a flashback and Yann Martel himself, who is the "visiting writer" (Martel 101) interviewing Pi many years after the tiger in the boat story. This technique of the intrusive narrator adds the documentary realism to the book, setting up, like a musical counter-point, the myth-making, unreliable narrator, Pi. The reader is left to ponder at the end whether Pi's story is an allegory of another set of parallel events.^[26]

The novel is a work of fiction set in the summer of 1977 that draws on places and historical events in India. The Patel Family's discussions of the political situation refer to the Emergency period of the mid-1970s, when Indira Gandhi's administration ruled by decree, curtailed press freedoms, and imprisoned political opponents. Pondicherry is a former French colony in India. It does have an Indian Coffee House and Botanical Gardens. The Botanical Garden had a zoo in 1977 but did not have any animals bigger than a deer. Munnar, the destination for the Patel family's vacation, is a small but popular hill station in Kerala. Madurai, also referenced in the novel, is a popular tourist and pilgrimage site in Tamil Nadu.

Piscine Molitor "Pi" Patel

Piscine Molitor Patel, known to all as just "Pi", is the narrator and protagonist of the novel. He was named after a swimming pool in Paris, despite the fact that neither his mother nor his father particularly liked swimming. The story is told as a narrative from the perspective of a middle-aged Pi, now married with his own family, and living in Canada. At the time of main events of the story, he is sixteen years old. He recounts the story of his life and his 227-day journey on a lifeboat when his ship sinks in the middle of the Pacific Ocean during a voyage to North America.