The Food of the Gods (also titled The Food of the Gods and How it Came to Earth) chronicles the creation of a substance called Herakleophorbia, by two men named Bensington and Redwood. Later dubbing their creation “Boomfood,” they soon discover that it can cause some animals and plants to grow to an enormous size.
To conduct further experiments with their new discovery, they create an experimental farm, and hire an elderly couple to tend to some chickens that figure into their experiment. However, the couple's attention to their duties does not work out, and some of the chickens run rampant throughout the countryside. To make matters worse, several other creatures such as rats and wasps get into the “Boomfood,” and also end up terrorizing the populace. A civil engineer named Cossar urges Bensington and Redwood to take responsibility for what has happened. The gentlemen go to work to wipe out the giant pests, and also end up burning the experimental farm down.
What little remains of the food then ends up being used on a number of human infants. Redwood uses some on his own son, causing him to grow enormous, much to the horror of his mother. Cossar ends up feeding some to his three sons as well, and some is even slipped into the meals of royal princess a Doctor is attending to. Unknown directly to Redwood or Bensington, the couple that was supervising their experimental farm also took some of the “Boomfood,” and have been feeding it to their grandson, Caddles. In the case of Redwood and Cossar's sons, a giant nursery is fashioned for the men to educate their offspring, including large playthings and large-type books.
As the children grow up, many of them find themselves in a world that is hostile towards their size and 'change.' The 'Sons of Cossar' prove to be quite adept and thoughtful. The eldest constructs himself an enormous bicycle, but has no place to ride it. The brothers then decide to build a road, before the little people among them decry their decimation of their property. The boys then decide to use their skills to build houses for the little people as a way to help them, but grow discontented and sour when their plans are shouted down and decried. As they grow from boys to men, the world has grown even more discontent with the giants, as it also seems that the “Boomfood” has somehow leaked into the world again, with outbreaks here and there with overgrowth of giant vegetation and various animals known throughout the countryside.
The young Caddles ends up being raised under the more worse of conditions, with the small town where he grows up placing him to work in a chalk-pit. However, his curiousity soon is piqued by a number of things concerning the little people among him. At one point, he wanders into London looking for answers, but his curiosity and questioning soon lead to his death.
The son of Redwood happens to chance upon the giant princess who was also fed “Boomfood” at a young age, and the two end up falling in love. As she is already affianced to a prince in a neighboring region, their affair is soon forbidden. However, the princess soon runs off with Redwood.
By this time, outrage against the giants has reached a fever pitch, with people planning to take up arms against the giants, in the wake of Caddles' 'rampage' on London, and Redwood's absconding with the princess.
Redwood's father is soon made aware of where his son, the princess, and the 'Sons of Cossar' are. He is also given a message by the normal-sized persons. Redwood makes it to their encampment, where the Cossars' father also dwells.
Within their dwelling, Redwood delivers the message to the giants and to Cossar. The demands are for the giants to leave, and go off to a place where they will not pro-create, but eventually die out, thereby letting their existence fade away as if they had never been.
These terms are shouted down by the giants, who refuse to just die out. Several are of the persuasion thaat they will fight, even though the small humans outnumber them by the millions. Redwood's son suggests that they also make more “Boomfood,” letting it loose on the animals and plants, as well as feeding it to the humans. His thinking suggests a point of view that would push the world to keep growing, instead of the backwards-thinking method of it's current society.
Redwood, instead of going back to deliver the giants' answer, chooses to stay with them and Cossar, as they prepare for war, for their right to live and thrive on the Earth.