This book tells the story of the Nowak family before, during, and after World War II. They are Polish natives who flee their homeland and create a life in England but not without suffering a great deal of trauma during and after the war.

"22 Britannia Road" begins as Silvana Nowak and her son Aurek are on a boat headed for Britain to meet her husband, Aurek's father, for the first time in six years. They were separated during World War II. It is quite obvious from this first chapter that Silvana has suffered from wartime trauma. The book jumps between the present day, post-war, and previous experiences in Poland and in France. As information is revealed about the past, the reason behind the actions of the characters in the present become apparent.

The chapters spent in Poland tell of Silvana and Janusz's lives before World War II from both of their perspectives. They were both young adults when they first met, dated, and expected the birth of their son. They married, moved to a small flat in Warsaw, and spent two happy years together with their son. When World War II arrived in Poland, Janusz felt it was his duty to enlist. At this point, their stories differ greatly.

Janusz ends up separated from his unit soon after joining it and meets up with two other soldiers, Bruno and Franek, who are leaving the country. The three men plan to secretly travel to England to join the military there, since the Polish army was being decimated by both the Germans and the Russians. By the time they reach Marseilles, France, one of the men is dead and the other two are exhausted. While in Marseilles, Janusz falls in love with Helene and plans on staying with her and her family permanently. Unfortunately, the German army is advancing south, so Janusz and Bruno leave for Britain to join the military and escape the Germans headed towards Marseilles. While they are in Britain, Bruno dies in a plane crash and Helene is shot and killed. At this point, Bruno's girlfriend says he is lucky to not be alone and suggests that he search for his wife and child.

At the same time as Janusz's story, Silvana and Aurek feel the pressures of occupation. They finally flee Warsaw, but Aurek is killed in the process. In her grief, Silvana finds another baby boy and swaps him for her dead son. She calls this little boy Aurek, seeing him as the replacement for her dead son. They spend years in the Polish woods and on various farms struggling to survive and suffering from wartime trauma. They are finally rescued by the British forces and placed in a refugee camp where Janusz finds them.

Upon arriving in Britain, Janusz brings his wife and now seven-year-old Aurek to the home that he has recently purchased at 22 Britannia Road. Janusz dreams of recreating the perfect British family, while Silvana simply wants a father for the little boy. After struggling to adjust and suffering from a rift in their relationship, the family is finally restored.