James and Sir Daniel combine to thwart William in his bid to buy the five ships belonging to elderly Captain Murchieson on behalf of devious banker Josiah Beaumont, whom Elizabeth sees as a bad influence on her son. William moves into his own flat, where he secretly sees Charlotte, though Letty finds out. Captain Baines is tricked into buying a piano to sell in Norway, but ultimately turns the situation to his own advantage.

Daniel is anxious to break the Liverpool to Manchester railway's transport monopoly of the Merseyside docks and rail board. Elizabeth suggests that they use the canal system to beat the railways. Daniel is initially unresponsive but sees the prospect of steamers being used on the canals. Samuel continues to develop his idea of mail order trading. James accepts a cargo with no questions asked or papers only to find it is from the proceeds of a robbery in Manchester.

James is importing jute from Scotland and is not happy to learn that Letty's mill-workers are repairing old jute sacks, which, given that she believes in a fair wage, is under-cutting him. They argue and she is injured but, to make atonement, he takes her on his next voyage. Daniel impresses with his generosity by buying Sarah a venue for a seaman's mission but he and Elizabeth are united in their desire to stop William seeing Charlotte. They plan to send him to London but he calls their bluff.

Max Van Der Rheede is imprisoned and James is free. He beats Samuel to the contract of transporting nitrate and sets sail with his first cargo. Against his orders Margarita accompanies him. She is pregnant and eventually gives birth to a son. James is overjoyed. Elizabeth, on the other hand, receives distressing news. Daniel's ship has sunk returning to England and he has drowned, making her a widow for a second time.

Still in Bulgaria having dropped off the disguised, fugitive Prince Alexander Onedin and Captain Baines are captured by Tsarists, a fifty thousand pound ransom being required for their freedom. By selling off some of her shares and four of her brother's ships, Elizabeth raises the money and travels to Bulgaria with Samuel to hand it over. However the captives have already been rescued by the quick-thinking Tom and James is far from grateful to his sister for her gesture, which, he claims, will ruin him.

The Doyles return to Liverpool and Samuel declares his love for Helen but Charlotte refuses to divorce him - whilst Sarah and Fergus spend time together. Elizabeth learns that Daniel is the new ambassador to Turkey, an appointment engineered by Marston's father so that she will be obliged to leave Liverpool and join her husband . Helped by Tom, for whom he has arranged a master's apprenticeship, James tracks down Burgess, who has stolen back the ship the 'Black Pearl'. However he lets him keep the ship and returns to Liverpool, finding his house full of children following a fire at Letty's orphanage.

William's death causes a rift between Charlotte and Samuel, not helped when they learn that William left his son twenty thousand pounds. Seth Burgess is duped by the infamous tavern-keeper Paddy West into paying him for a crew to sail to New York with James. However they are not seamen but largely European immigrants, including a Count and his pregnant wife. James is reluctant to put them ashore on Ellis island but changes his mind after the count saves him from an attack by a fugitive murderer. Captain Baines recovers the money from West by arm -wrestling him.

As the council election approaches, Elizabeth, equally disapproving of her husband's interest in the Manchester Ship Canal and his rival Beaumont's plan to enrich himself with his 'new' Liverpool, ensures that each hears of, and publicizes, the other's plan so that both lose the election to her candidate, Marcus Simmons. Daniel then announces that he will be standing as a Manchester M.P. James, stuck in Ireland thanks to port inspectors with vested interests, finally returns to Liverpool for the birth of his son, though the child is weak and is not expected to survive.

Five years have elapsed. Onedin is a prisoner in a settlement in South America from where he is rescued by Captain Baines, and they return to Liverpool. Macaulay, a wealthy Australian, keen to invest in the shipping trade with South Africa, does business with the Onedin's but when the bank crashes, the Onedin's lose out as their collateral is taken. Robert loses his shop and James's ships are forfeited but he manages to get them out of port before Macaulay claims them.

Having exposed Macauley's insurance scam James proposes to Letty, who accepts. Daniel also returns to Liverpool, now a very wealthy man. Robert considers opening a department store and travels with Captain Baines and Samuel to New York, where he is robbed and very nearly press-ganged. James takes on a voyage to import some sheep but it causes him to postpone the wedding and Letty, as a consequence, declares the engagement and wedding off.

Letty tells James she invested in William's steam engine project and he buys a flour mill in her name, sailing to Pennsylvania to buy loose grain from an ex-Cavalry officer who drives a hard bargain. James gets what he wants after a drinking bout but the grain, known as dead man's cargo, starts to shift when the ship hits a storm and needs to be moved else the ship could capsize. A man dies in the process. Daniel and Elizabeth rekindle their old flame but their decision to tell William his true parentage proves to be unwise.

James and Captain Baines sail to Palermo to pick up emigrants for America. Whilst James is ashore with his Sicilian agent Benito, several Mafia bandits led by local don Ranocci take over the ship and in the subsequent gun-battle the mate is killed and Captain Baines and the crew taken hostage. They will be released if James gives Ranocci the money taken from the locals for their voyage but James has other ideas and leads the oppressed Sicilians against the Mafia. At home Letty goes into business and William is as disapproving of his parents' relationship as they are of his intense friendship with Charlotte.

William takes a Frazer ship out in fog and gets it in a collision with one of the Onedin ships. It is arranged that the elderly, weak Captain Oliphant should be held responsible. Oliphant later kills himself and William is filled with remorse. Elizabeth is relieved to see that he possesses some humanity. However he is seeing Charlotte, supposedly the fiancée of a dissatisfied Samuel, who wants a more active life than working in the family shop. At dinner Samuel's father Robert chokes on a bone and dies.

Letty tells James that she is pregnant and Charlotte gives William the same news. He is stunned and, as he does not love her, refuses to marry her - although she has confided in Samuel that she believes they will wed. Samuel takes the news badly and, when he and James, sailing to Ireland, come across a deserted steamer full of high explosives, feels sufficiently reckless to help James put the cargo overboard, though they are successful and claim the salvage rights. William turns twenty-one and inherits his mother's share of the Frazer yard, which he intends to sell.

James learns of Charlotte's situation but refuses permission for her to marry William, whom he regards as worthless, and sends her out of Liverpool to have her child. He also encourages Daniel to stand against the greedy Beaumont as a councillor to thwart the banker's aim to take more land for himself if elected though Elizabeth is still unhappy about her husband's support for the ship canal. Captain Baines brings home a ship from South America, whose dying captain is an old enemy of his. Baines falls for the man's wife and considers buying the ship when her husband dies but James beats him to it.

Newly elected to Parliament Daniel joins with Elizabeth to prevent William from selling the Frazer Line to an apparent consortium, actually a front for Beaumont. To take his mind off his son's death James sails to Africa with Captain Baines to find diamonds but they end up adrift in an open boat for three months. Letty never doubts that he will come back and, on his return, he gives half of the Onedin Line to Samuel, who has married Charlotte just in time for the birth of her son.