[2][3] The book focuses on a religious sect called God's Gardeners, a small community of survivors of the same biological catastrophe depicted in Atwood's earlier novel Oryx and Crake.

They are vegetarians devoted to honoring and preserving all plant and animal life, and they predict a human species-ending disaster, which they call "The Waterless Flood".

Much of the story is told through flashbacks with the two main characters separately surviving the apocalypse described in the previous novel, each reminiscing about their time in God's Gardeners and the events that led to their current situations.

Toby is a young woman who loses her parents under tragic circumstances that may or may not be due to the corporations and is forced to live off of the grid, working as a barista at SecretBurgers, a shady meat burger joint.

She soon encounters the unwelcome attentions of Blanco, the psychopathic manager of the chain, who has a reputation for sexually assaulting and murdering the women in his employ.

Ren joined the God's Gardeners when her mother, Lucerne, left her HelthWyzer scientist husband after falling in love with Zeb, a member of the sect.

Later, Ren enrolls in a Dance Calisthenics courses at the Martha Graham Academy, until Lucerne is unable to pay and she drops out.

Eventually, Ren becomes a sex worker and trapeze dancer in the sex-club Scales and Tails, part of SeksMart.

Toby barricades herself in the luxury spa as the plague spreads, utilizing the skills of foraging she learned with the God's Gardeners to survive.

In this hyper-capitalist society, scientists work for and answer to the global corporations, creating products upon which the citizens become dependent.

Many of these new animals are formed and utilised for their by products, including a combination of goat and spider to yield silk bulletproof vests and 'Mo'Hairs', which are colourful sheep to make better, natural wigs.

In this novel, the middle of trilogy, Atwood gives us more detail surrounding the childhood of Crake, highlighting his connection with the God's Gardeners that inspired his plague, and the conception of the MaddAddam group.

Atwood explains who the people that Snowman had seen at the conclusion of Oryx and Crake are, with it being Toby, Ren, Amanda and the criminals they incapacitate.

[12] For both Oryx and Crake and The Year of the Flood, Atwood donated naming rights to characters in the novel to charity auctions.

[18] On the November/December 2009 issue of Bookmarks, the book received (3.5 out of 5) stars, with the critical summary saying, "As in Oryx and Crake, Atwood imbues The Year of the Flood with her deep, dramatic vision of the devastation wrought by our destruction of Earth".

The novel was selected for inclusion in the 2014 edition of CBC Radio's Canada Reads, where it was defended by Stephen Lewis.