Though it raises complex philosophical and religious questions, Life of Pi's plot is almost ridiculously easy to summarize. We'll take you through the main events, but remember much of the novel happens through digression and in Pi's meditations sprinkled throughout the novel.
The book doesn't begin with Pi, but with an "Author's Note." We learn how the "author" (who shares some of Yann Martel's biography) found Pi's story. We should note one point of complexity: the author admits any mistakes in the narrative are due to him and not Pi, since he's presumably put together Pi's story from interviews, notes, and Pi's diary. What we read, then, in Part 1 and Part 2 is Pi's voice as the author has written it. And then, without further ado, we launch into Pi's story.
Part 1 details Pi's childhood in Pondicherry, India. His father owns a zoo and Pi spends a lot of his time thinking about animals. But zoology is only one of Pi's passions: he also loves religion. He's a Hindu from birth; then at fourteen he adds Catholicism to his repertoire; at fifteen he adds Islam. He's inquisitive, joyful, and an all-around wonder of a human being. Things, however, aren't so swell in India. The Prime Minister, one Mrs. Indira Gandhi, institutes martial law (this is in the mid-1970s – see "Setting" for more). Pi's parents decide to leave India. They sell most of the animals and pack up their belongings. They board, along with some of the animals they're selling to North American zoos, a Japanese cargo ship. They're headed for Canada.
All of Part 2 takes place at sea, but without many of the characters we met in Part 1. Tragedy strikes and the ship sinks halfway to the Midway atoll. No one survives except Pi and a menagerie of animals: a zebra, a hyena, an orang-utan, and a Bengal tiger. All these creatures, including Pi, are packed into a 26-foot-long lifeboat. Before long, as you'd expect, there's some bloodshed. The hyena kills the zebra and the orang-utan. And then the tiger, whose name is Richard Parker (a.k.a. RP), kills the hyena.
Richard Parker and Pi, however, work out an uneasy living arrangement. And Pi slowly trains RP until he's more or less master of the lifeboat. Pi is often despondent, though Pi and RP seem to do well for a while. Pi catches fish and he has a few tools (like solar stills) from the lifeboat's locker. It's true that Pi's survival skills develop, but it's also true that he's just lost his entire family. Pi is alone except for a man-eating tiger. He endures through cleverness, prayer, and willpower.
At the end of Part 2, however, some strange things happen. Pi meets another castaway on this gigantic ocean who tries to eat him. Instead, RP eats the castaway. And then Pi lands on an island made entirely of algae. Pi and RP are malnourished at this point and it's not far-fetched to think Pi has gone mad. The chapter ends with Pi and RP landing in Mexico. RP bounds off into the jungle without so much as a goodbye.
Part 3 isn't long at all. Two civil servants for the Japanese Maritime Department in the Ministry of Transport interview Pi to try and shed some light on the sinking of the cargo ship. While they don't get any answers about the ship's sudden shipwreck, they do get Pi's story. When they question the more implausible portions of Pi's story, Pi delivers an impassioned defense of "the better story." To prove his point, he tells a version of his story without any of the animals mentioned above. It's an utterly ghastly story since human beings, instead of animals, literally tear each other to shreds.
Pi asks the investigators which story they prefer. They prefer the story with animals. There's some wrapping up, but the book basically ends there. The reader has to decide if Pi has concocted a totally elaborate story with animals instead of human beings to explain the horrific events on the lifeboat. Or if, like Pi suggests, she should believe "the better story."