Dr. Mark Muir, a young American metallurgist, persuades American tycoon JP Morgan to hire him for the biggest shipping project the world has ever seen: RMS Titanic, at the Harland & Wolff shipyard, in Belfast. The shipyard's visionary Chairman takes the young scientist under his wing, introducing him to Belfast's Protestant elite. Mark quickly catches the eye of the charming, albeit spoilt, daughter of a magnate: Kitty Carlton. But he is also intrigued by a very different woman; Sofia Silvestri, an immigrant's daughter. Belfast, seen through Mark's eyes, is a city ridden with divisions of class and religion, from which, as a stranger, Mark should be far removed. But we soon discover that Mark is a man with a past mysteriously connected to the Catholic suburbs of Belfast.

Dr. Mark Muir's real name is Marcas Malone, and he is the son of a Belfast Catholic dockworker, Sean. Sean is an old drunkard, broken by a life of unimaginable harshness. His only remaining pride lies in Mark. Now, Sean is worried that if Mark's identity were to be disclosed, he would lose his job at the Protestant - managed shipyard. But Mark is careful and guarded. He starts finding out things about the steel used that lead him into conflict with chief designer Thomas Andrews. In the meantime, social tension escalates. A prominent figure in the labor movement, Jim Larkin, is organizing the workers in Belfast. While Kitty Carlton seduces Mark with her elegant charms, Sofia gets more involved in her fight for freedom, which she interprets in a personal way, turning down her father's apprentice, Andrea Valle, much to her father's grief.

Mark has put his father up in a small hotel. We learn that another man is looking for Mark, someone that Sean fears. Mark's job has made him closer to Sofia Silvestri. Sofia is charmed by Mark: he seems genuinely interested in her. Sofia's friend Emily warns to be careful. But Sofia has other worries. Her father is encouraging Andrea to fight for her. But Sofia won't be forced. In the meantime, Mark discovers a problem with the steel used to build the ship. But science is put to test by the divides in Belfast. The Protestant magnates, worried by the success of the Union, call in the Army to boycott a peaceful march. The Army sabotages the march in the Catholic area, causing accidents that seem organised by Catholic workers. Mark is there to show his respect for the workers.

Losing his job is not Mark's only problem. Sofia knows his truth. Mark tells her everything. Even about Siobhan and the baby. She eventually forgives him. It is also time for Mark to reconcile with Sean. Mark's situation seems to get better still when JP. Morgan arrives. When told the reason why his chief metallurgist has been fired, Morgan has him immediately reinstated. Mark starts looking for a viable alternative to the double hull, an alternative he finds in higher bulkheads. General Elections are in sight. Home Rule for Ireland is at stake. The possibility that London putting a stop controlling the island is strongly opposed by the Protestant minority, which fears the power the Catholic majority would get. Emily persuades her brother Michael to stand for Parliament, and Pirrie helps and supports his main counterpart in the shipyard.

The high staked General Elections are drawing closer. The magnates have their own candidate, the Unionist extremist Albert Hatton. The fact that Pirrie does not support Hatton makes him an enemy of the ruling class. Michael is campaigning for Labour. His sister Emily helps him. But she gets arrested for giving out leaflets. This is a political measure, and Emily is only the scapegoat. On the ship front, Mark's proposition to erect higher bulkheads to defend Titanic is crushed by Ismay, the Chairman of White Star Lines, the company Titanic is being built for. When the elections occur, Albert Hatton wins a handsome majority. The third candidate, Michael, only gets a very small number of votes. Protestant and anti Home Rule extremists fume with rage and hatred, and Michael is assaulted, cruelly beaten and forced from Belfast. His brother Conor has become a terrorist and has taken lives.

An accountant from the United States, Samuel, makes Mark feel jealous. Samuel is handsome and witty. He is American and unaware and uninterested in divisions. For Sofia, he represents a real temptation: Pietro is better and Mark still can't leave his job. Mark is still uncertain: he still hopes to find his daughter. Mark discovers what the girl's name was: Sarah. The girl might live in a small village outside Belfast. But the girl, who had indeed been living there, has left. They have moved to Belfast but no one knows where. Andrews fights, and looses, a memorable battle to equip Titanic more life boats. And while Pirrie and Churchill try to campaign for Home Rule in Belfast, the divide between the Catholic and Protestant communities has grown. Lord Pirrie, by now disillusioned with most of his liberal principles, falls ill.

The time has come for the great ship to leave for the New World. As Morgan always wanted, Titanic's maiden's voyage will become one of the first great PR events. Sofia and Joanna Yaeger are friends and she gets her a job as an illustrator for the New York Times. Pietro uses most of his money to buy her a ticket. Mark himself only gets on board by chance. The group also includes Jack Lowry, a young riveter we met since the beginning of the story. Violetta with the baby, whom Michael MacCann, has come back to marry. Joanna will be onboard – and so will Kitty, by now an acclaimed actress. A little girl by the name of Sarah, with her mother, will board Third Class. Neither Mark nor his daughter are aware of their presence onboard the Titanic. And, while the ship sails for New York, and Mark and Sofia finally find happiness and reconciliation, we are left asking ourselves: who amongst our characters will survive the great disaster?