Jolyon makes a decision that will break apart the close-knit Forsyte family and change his life forever. Winifred married Dartie against her brother and father's wishes, but they are determined to protect the family all the same. Soames is made happy when Irene accepts his proposal of marriage, but she had conditions because she knows she does not love him. June is all grown up and in love with a promising young architect, Phil Bosinney who she is determined to marry.

Bosinney, the young architect, continues construction work on the Robin Hill house for Mr. Soames and his unhappy wife Irene. Soames and Bosinney disagree and ultimately fall out over budget matters, while feelings continue to develop between Bosinney and Irene.

Old Jolyon makes an offer on Robin Hill presuming that Soames will no longer want it. He feels it will be a fitting place for the family and his last days. June meets her father and her extended family for the first time. As Old Jolyon is buried after his sudden death, his family grieves the loss. Dartie is seriously in debt and Winifred finds out.

Soames' hired detective locates Irene in Paris and he again pays her a visit begging her to return as his wife. He is desperate for a son but she flatly refuses him.