The novel takes place on two planets, Anarres and Urras. Anarres is an isolated, desert-like world where people live by strict communal and anarchist principles, while Urras is a lush and wealthy planet divided by class and political systems. The story follows Shevek, a physicist from Anarres, as he travels to Urras in hopes of sharing his groundbreaking theory of time.

Shevek’s journey begins with his controversial decision to leave Anarres. Spaceships rarely come to Anarres, and its people are wary of outsiders and those who wish to leave. A mob protests his departure, but they fail to stop him. As the spaceship takes off, Shevek reflects on his partner, Takver, and their child, whom he has left behind.

On Urras, Shevek is greeted warmly and taken to Ieu Eun University in the state of A-Io. He is amazed by the planet’s natural beauty, wealth, and the luxurious lives of its upper class, which starkly contrasts with the harsh simplicity of Anarres. During his stay, he observes Urras’s political and social systems, including its free press in A-Io and its strict control in the communist state of Thu.

Through flashbacks, we learn about Shevek’s upbringing. From a young age, he showed an exceptional interest in physics and time. Raised in a communal nursery, he had little contact with his parents. His father was a builder, and his mother, Rulag, left him for work. Anarres society values equality and discourages individuality, which often made Shevek feel out of place. As he grew older, he pursued his passion for physics, eventually meeting Takver, a marine biologist who became his life partner.

On Urras, Shevek begins to question his surroundings. He realizes that the A-Io government is using him for his scientific knowledge. Chifoilisk, a fellow physicist, warns Shevek that once his work is complete, he may be discarded. Shevek also discovers the stark inequality on Urras. The wealthy live in comfort, while the poor struggle in harsh conditions.

Shevek experiences both personal and professional challenges. He feels isolated and is frustrated by the political manipulation of his work. He also learns that the wealthy exploit the lower classes, similar to the history he was taught about Urras during his education on Anarres. Despite these struggles, Shevek continues to work on his theory of time, which could enable faster-than-light communication through a device called the ansible.

Shevek is drawn to the anarchists on Urras, who resist the oppressive government. He joins them at a protest, which turns violent when the military intervenes. To escape danger, Shevek seeks refuge at the Terran (Earth) embassy. There, he meets Keng, a Terran ambassador, and shares his theory with her. Shevek insists that his work should belong to all planets and not be controlled by a single government.

Shevek’s journey also highlights his relationship with Takver. On Anarres, they faced hardships together, including being separated due to work assignments and enduring a severe famine. Despite these challenges, their bond remained strong. Takver supported Shevek’s nonconformist ideas, which often put them at odds with Anarres society.

In the end, Shevek completes his theory and decides to return to Anarres. On the journey back, he reflects on his decision and wonders if he will be accepted. A fellow passenger from Urras asks if he will be allowed to visit Anarres, symbolizing the hope for a future where the two planets can connect.

Through Shevek’s experiences, the novel explores themes of freedom, inequality, and the tension between individual desires and societal expectations. It also challenges readers to question what it means to live in a just and fair society.