In the enchanting setting of 13th-century Lincolnshire, England, we meet Catherine, affectionately called Birdy, a spirited 14-year-old girl native to an affluent family estate. Her life is a tapestry of adventure and mischief, largely encouraged by her father, Lord Rollo, and mother, Lady Aislinn. With the support of her nurse, Morwenna, and her close friend, Perkin, a peasant boy, Birdy revels in the freedom of her youthful days. However, the comfort of her lavish lifestyle is shaken to its core when Lord Rollo discovers that their family's finances are dwindling, leading him to contemplate an arranged marriage for Birdy with a wealthy suitor.
As Birdy navigates the tumultuous waters of adolescence, marked notably by her first menstruation, Morwenna steps in to guide her with tenderness and understanding. Meanwhile, Lady Aislinn faces heartbreak after yet another tragic pregnancy, leaving Birdy worried about her mother's health. Driven by a fierce desire to maintain her autonomy, Birdy resorts to creative and often humorous ways to fend off her numerous suitors, much to Rollo’s escalating frustration.
The introduction of Aelis, a beloved friend, adds a new dimension to Birdy's life. However, her heart takes a heavy blow when she learns that Uncle George, whom she has secretly admired, has wed Ethelfritha, a wealthy widow. Just as matters worsen with Aislinn’s pregnancy complications, adventure knocks again with Sir John Henry Murgaw—better known as Shaggy Beard—who relentlessly pursues Birdy, showering her with gifts and challenging her to marry him.
With tensions building, Aelis faces an imminent and rather alarming arrangement to marry a mere nine-year-old, which also leads Robert to grapple with his unspoken affections for her. Seizing a moment of opportunity, Birdy decides to donate Shaggy Beard's gifted purse to Robert, hoping to help him win Aelis’ heart. Yet, her journey takes another twist when she discovers that Uncle George’s legendary exploits are mere fabrications. Despite Ethelfritha's enticing suggestions to join her in a life of excitement, Birdy grapples with a painful choice: to relinquish her family bonds would mean losing herself entirely.
In a bittersweet turn of events, Birdy commits to preserving her family’s honor by marrying for duty rather than love. But upon returning home, she is confronted with an urgent crisis—her mother’s labor has taken a troubling turn. Lord Rollo rises to the occasion, providing much-needed support to Lady Aislinn as they welcome twin daughters into the world.
The anticipated day for Birdy to depart with Shaggy Beard arrives, steeped in tears and heartbreak. Yet, Rollo's intervention alters her fate by demanding that Birdy stay with him. Shaggy Beard refuses to relent, leading Rollo and him to an arduous duel. Despite his unrefined sword skills, Rollo emerges victorious, although Shaggy Beard’s unexpected retreat allows him to slip away and avoid facing the consequences of his pursuit.
As Birdy reflects on her transformative journey, she pens her thoughts in a diary, promising to safeguard her hard-won freedom amidst the constraints of her reality. Her carefree moments with Perkin juxtapose sharply against the whirlwind of emotions she has experienced. Just as she prepares to embark on yet another chapter of her life, a new suitor approaches, hinting at fresh beginnings on the horizon.
