The untimely death of her mother allows seventeen year old Helen the realisation of a lifelong dream - sailing the worlds oceans with her adored Papa, Captain George Winter. Aboard the schooner Eden, Helen is finally where she wants to be. In the early years of Victoria's reign it was not unheard of for a woman to be so independently minded, Helen relishing the life aboard the immigrant ship. During last stage of their voyage from New Zealand to Fiji, the Eden encounters a cyclone and founders. Captain Winter orders a capable crewman, Twenty-five year old Gavin Smith, to take his daughter, her companion Alice, plus eight other passengers and crew to safety in a long boat when it's clear the ship is doomed.
Torn from her father and adrift with strangers, Helen must endure her grief and the perils of the open ocean. Cast up on a tropical paradise, the survivors become reliant on each other, Helen especially so on the young man who has become her protector.
Fortune smiles on the group and they find an abandoned village, the occupants the victims of slavers, the huts a refuge for the survivors. Together they create a community, harvesting the bounty of sea and exploring their Garden of Eden. During one such trip Helen acknowledges there is something between them, Gavin going so far as to kiss her, but he has a past which makes him reluctant to pursue the relationship. A surprise party for Helen's eighteenth birthday on their return only serves to drive Helen and Gavin apart with too much left unexplained.
Soon after their paradise is shattered with the return of the slavers, with two thirds of the survivors captured and carried off. Helen narrowly avoids capture. Gavin and a sailor from the Eden recover Helen after witnessing the enslavement of the others. The trio leave the burned out village and venture further inland. They are soon discovered by a hunting party who take the three back to their own village on the other side of the island, welcoming them into their Fijian community.
In the safe atmosphere of the native village, Helen and Gavin have an opportunity to explore the feelings that had been growing between them. Gavin tells Helen something of his shadowed past and that he's more than just a humble sailor. Interrupting a moonlight dalliance, the Captain and crew of the American ship, the Zephyr, land on the island. Captain Wallace agrees to take all three aboard his ship. The Captain, along with his wife Miriam, are regular visitors to the islands as Beche de Mer traders and agree to help the young people rescue their enslaved friends.
Knowing something of the habits of the blackbirder's, the Captain suggests they sail to Suva because the slavers have a stronghold on the nearby island of Ovalau.
The Captain's wife is something of a pious and correct lady, taking Helen under her wing while Gavin and Ned are set to work as crew. During the voyage Helen and Gavin continue their interrupted dalliance in secret, consummating their love in a stormy night of passion. They are discovered and Gavin agrees to a shipboard marriage by the Captain, who is a Baptist minister.
On arrival at the harbor town of Suva, it is discovered that the Eden had not been lost but in fact brought safely to port. Helen is told that her father is gravely ill. With the resurrection of his beloved daughter Captain Winter rallies, but Helen must now bear the loss of another loved one, Gavin shipping out on the Zephyr to take part in the rescue of the castaways held on the lawless island of Ovalau.
Left to languish on Viti Levu, Helen and her father receive an unexpected visitor. Gavin's twin brother arrives in search of him, Gregory not impressed when he learns that Helen and Gavin are married, unable to believe that his wayward brother, the heir to an Earldom, would so demean his family honour. Helen is aware of Gavin's true name and rank, but hadn't taken it seriously. Faced with his brother's scorn, Helen doubts both herself and her love, even the validity of her marriage.
Gregory Ashworth and the Valiant sail to join forces with Captain Wallace in mounting an assault on the slaver's stronghold. The triumphant rescue party return to Suva with the freed slaves, and Gavin, ill from a flogging by the slavers. While waiting for Gavin's return, Helen is approached by a sailor she'd met previously and who claims to be from the Valiant. He is a deserter and sees kidnapping Helen as a revenge on the Ashworth brothers. He drugs Helen and hides her away.
Gavin doesn't recover for several days, and Gregory, not believing that Gavin is married, ignores pleas from Captain Winter for help. When Gavin is lucid enough to ask for Helen, Gregory realises he's has made a monumental mistake. Together the brothers search Suva, the outcome frustratingly unsuccessful. The kidnapper is captured, confessing where he's hidden Helen in return for the promise of gold and safe passage.
Helen is found but dangerously ill, Gavin believing her dead until the Valiants surgeon confirms otherwise. Helen is made well and reunited with her father and friends. Adding to Helen's joy is finding out that her beloved Papa has found true love with her bosom companion Alice.
With the reason for his leaving England now no longer a barrier, Gavin can return and take up his rightful place, refusing any suggestion that Helen should not be by his side.
They renew their love in a secluded cove, using the time together to settle any doubts about their future as man and wife. The wedding of her father to her best friend is also a farewell celebration before the breakup of the friendships forged by adversity. Gavin's staunch love is enough to banish any fears Helen might have about his aristocratic family's reception.
All future worries are put aside as they wave goodbye to the tropical Fiji islands, their future together promising to be possibly the biggest adventure yet to come.