In early 20th century North Wales, scientist Thomas Trelone embarks to hormonally enhance the cognition and lifespan of sheep-dogs, eventually succeeding in creating a viable puppy, Sirius, just as his daughter Plaxy is born.

After a year, Sirius eagerly returns home to meet Plaxy again and discuss with Thomas about finding his place in the world by pursuing personal growth.

Partly to comply with his desires, Thomas decides to take Sirius to the University of Cambridge and reveal him for the first time to his most trusted colleagues, who react with amazement.

Sirius's time at Cambridge partly satisfies his mental pursuits, but his well-being, self-control, and fitness decline due to homesickness, pampering, and inactivity.

However, when Elizabeth arranges a meeting with Reverend Geoffrey Adams, he is disappointed to learn that human religion centers more on doctrine and mythology than love or spiritual truth.

Geoffrey is killed and Sirius witnesses Thomas being crushed to death during a bombing, with Elizabeth succumbing shortly after to shock from believing to have lost his son in battle.