In 1926, Fleur Forsyte delves into her past, to find out why her life has been ruined by family  secrets. Her exploration takes her back to 1886 and the story of Irene, her father’s first wife.

The Forsyte brothers - James, Jolyon and Swithin - are high Victorian, nouveau riche and very pleased with themselves. James’s son, Soames Forsyte, likes to own things. He is married to the beautiful Irene, whom he has ‘collected’ alongside his many paintings. Irene was coerced into the marriage, which is a disaster - she can’t bear Soames to touch her.

Jolyon Forsyte’s granddaughter, June, becomes engaged to a handsome young architect, Philip Bosinney. Soames commissions Bosinney to design and build a house at Robin Hill. There is an immediate spark between Bosinney and Irene, who are both outsiders.

Irene is determined to keep her marriage vow - until Soames declares that a promise made under duress doesn’t count. Suddenly feeling free of Soames, Irene and Bosinney plan to elope. Rumours spread about them and, following his father’s advice, Soames rapes Irene in an effort to 'reclaim' her. When Bosinney goes hunting for Soames to enact his revenge, he is killed in a freak accident.

Irene leaves Soames and disappears. The Robin Hill house is sold to Jolyon, who one day finds Irene in the bluebell coppice where she and Bosinney first kissed. Old Jolyon and Irene become increasingly close. When Jolyon dies, he leaves Irene an income. This is administered by Jo Forsyte, June’s father.

By 1900, Soames is rich and wants a child. Still obsessed with Irene, he tracks her down. She flees to France, supported by Jo, but Soames follows her obsessively. Jo and Irene develop a deep friendship, which slowly morphs into love, giving Soames grounds for divorce. Irene and Jo marry and have a son named Jon. Soames marries Annette, the young daughter of a French restauranteur, and soon Fleur is born.

The final scene of Part 1 flashes forward to 1920 when Fleur and Jon meet by chance at June’s art gallery - kicking off a whole new series of dramas.

It is 1926, and Fleur, Soames’ daughter, now a grown woman, begins to investigate the Forsyte family secrets which have had such a ruinous impact on her own life.

We go back to 1920 when she meets her cousin Jon for the first time and she is instantly fascinated. Soames warns Fleur she must have nothing to do with that side of the family, but she sets out to pursue Jon all the same. Michael Mont, a young man recently returned from the War, has his own plans to win Fleur’s heart.

Fleur and Jon embark on a series of secret meetings while they try to work out the nature of the family feud. Irene tells Jo he must not reveal her history with Soames and Bosinney to Jon, and Jo agrees against his better judgement.

Back at home Fleur joins her father in a mutual dislike of Prosper Profound, her mother’s lover. Profond reveals the family secret to Fleur - Jon is the child of Soames’ first wife Irene. Fleur is shocked but decides not to tell Jon. Instead, she pressures Jon to marry her. When Jon tells his father he is engaged to Fleur, he finally learns that Soames was once married to his mother and raped her. Increasingly desperate, Fleur begs Soames to intervene with Irene but it’s no use. Jon bids Fleur farewell and leaves the country. Fleur, shattered, marries Michael Mont.

Six years later, Fleur, now a mother, is volunteering during the General Strike, when she meets Jon again. Although he is happily married she sets out to rekindle their affair. Manipulating her child’s illness and her husband’s schedule, she engineers a series of seemingly accidental meetings with Jon, always in the right place at the right time. Eventually she takes him to the coppice at Robin Hill where they make love. Jon immediately says he must tell his wife Anne, but she already suspects. Anne tells Jon she’s pregnant and he promises never to see Fleur again.

Distraught, Fleur is comforted by her father. Later that night she causes a fire by accident in the house. She longs to die in the fire and escape her misery, but Soames intervenes and saves her, losing his own life in the process.

We leave Fleur with Michael, who has stayed by her side all along.