In late 19th-century Australia, Sybylla Melvyn comes of age while her family undergoes serious financial struggles. Though Sybylla starts life wealthy, her father moves the Melvyns to a ranch on Possum Gully in an attempt to make a career trading stocks. He fails, and the family turns to dairy farming to make a living. The labor is hard and unrewarding, and Sybylla longs for the chance to make something of herself.
Sybylla gets in frequent disagreements with her mother, and when Mrs. Melvyn writes to her own mother, Mrs. Bossier, the older woman offers to take Sybylla in at the Bossier estate. At the estate, called Caddagat, Mrs. Bossier promises to refine Sybylla into a proper lady and prepare her for marriage. Sybylla eagerly leaves Possum Gully and falls in love with life at Caddagat, where she lives with her grandmother, her Aunt Helen, and her Uncle Julius. Also residing at Caddagat is the laborer Frank Hawden, who makes several advances on Sybylla despite her repeated rejections.
While at Caddagat, Sybylla meets two young men: Harold Beecham and Everard Grey. Harold Beecham owns the neighboring estate, and he and Sybylla quickly begin a playful, teasing courtship. Everard Grey is Mrs. Bossier’s adopted son, and when he visits for Christmas, he encourages Sybylla to take up a career on the stage. Sybylla, who loves to perform, is taken with the idea, but Mrs. Bossier insists that such a career would be unladylike and improper. Eventually Everard and Mrs. Bossier find a compromise, and agree that Sybylla may visit Sydney with Everard the following year.
Sybylla and Harold’s relationship develops, and eventually he asks her to marry him. She is surprised, but she accepts. When Harold leans in to kiss her, however, she panics and strikes him with a whip. Sybylla is horrified by her unwomanly behavior, but Harold forgives her, and the two begin a secret engagement.
Their romance is interrupted when Harold abruptly loses his fortune. He offers to free Sybylla from her obligation to him, but she insists on remaining betrothed, believing that she can help him in his new life of poverty. Harold plans to set out to find a new fortune, and Sybylla proposes a plan: they will not see each other for four years, and if at the end of that time Harold still wants to marry her, then she will marry him. Harold agrees, and the two separate.
Soon after, Mrs. Melvyn writes to inform Sybylla that Mr. Melvyn has fallen into debt to a man named Peter M’Swat. To help the family, Sybylla will need to leave Caddagat and work as a governess for the M’Swat family at their home in Barney’s Gap. Sybylla is horrified. She tries to refuse, but Mrs. Bossier insists that Sybylla obey her mother. Thus, Sybylla leaves Caddagat and goes to live with the M’Swats.
The M’Swats’ home is filthy and squalid, and the M’Swats themselves are appallingly ignorant. Sybylla has no access to the cultural refinement she desires: Mr. M’Swat can only barely read, so the only literature about the house is in the form of farming records and newspapers. And though the M’Swats have a piano, it is broken and out of tune. Sybylla’s work as a governess is difficult, since the M’Swat children look down on the Melvyn family and Mrs. M’Swat refuses to discipline them. Finally, Sybylla exerts her authority over the children and manages to earn their respect.
Sybylla is deeply depressed by life at Barney’s Gap. She writes to her mother and grandmother, begging to return to Caddagat, but they insist that she remain at Barney’s Gap for at least another year. Sybylla’s hopelessness eventually drives her to a complete mental and physical breakdown. She becomes bedridden, and the concerned M’Swats send her back to her family at Possum Gully.
Mrs. Melvyn is cross with Sybylla for her behavior at the M’Swats, and the relationship between mother and daughter grows increasingly contentious. When Mrs. Bossier offers to bring one of the Melvyn children to Caddagat, Mrs. Melvyn sends Sybylla’s younger sister Gertie instead of Sybylla. While Gertie is at Caddagat, Harold returns to the neighboring Five-Bob Downs––he has earned a new fortune. Sybylla assumes that Harold will prefer her pretty younger sister, so she writes to him and calls off the engagement.
Sybylla falls into the monotony and toil of life at Possum Gully, until her boredom is interrupted by the sudden arrival of Harold Beecham. The four years have passed, and he, having taken her rejection as a joke, has come to marry Sybylla. With difficulty, she turns down his proposal. She realizes that she could one day marry a man, but that man needs to have suffered as she has so he can truly understand her.
Sybylla ends her story alone, with no prospects, musing on the nature of ambition. It seems pointless to her now, since everyone eventually dies, but she throws off her pessimism and rejoices in her status as an Australian. She is proud of her nation and of the peasants who make it the country it is. She takes in the Australian horizon—accepting that she is simply a woman of the bush—and wishes her reader good night.