Britain in the recession-torn early 1930s. Shipbuilder David Barr demonstrates a prototype new design for a cargo ship which he believes will revive the moribund British shipping industry. In the face of reluctance from the board of his company, Burns MacKinnon, and an absence of orders, he orders work to commence on twenty ships in order to minimise costs. In order to win the board's support, he deceives them into believing that a government Bill to revive the shipping industry by imposing quotas favouring British shipping is certain to be passed, even though he knows that the Bill has already failed.
An unscrupulous local businessman, Manning, offers to buy the design, or any ships which the yard can build, but Barr rejects him, saying that the ships will end up overseas with no benefit to the British industry. Despite the protest of the board's chairman, Lord Dean, Barr carries the board with the support of June MacKinnon, a trustee of the company's founder and the fiancée of Lord Dean.
When it emerges that Barr misled the board, Dean announces his resignation and June withdraws her support. Barr is left to keep production going with his own money. Barr attempts to secure funding from financiers without success. Payday arrives and there is no money to pay the wage bill. Barr pays a visit to June to ask her to influence Lord Dean to intervene, but June, who is secretly falling in love with him, is hurt by the mercenary reason for his visit and refuses. Organising a press conference to generate interest in his scheme to revive the industry, Barr makes a final effort to persuade a local banker, MacLoed, to loan him the money he needs, but is rebuffed because he has no orders. He receives a visit from Manning, who again offers to buy the vessels, but Barr again turns him down.
In the yard, one of the workers, a plant installed by Manning to agitate the workforce, attempts to stir the workers in to action, but Barr makes a stirring speech imploring the workers to stand behind him for the good of all their futures and wins them over. June, watching Barr's speech, is overcome with admiration and agrees to support him. However, they still need the consent of Lord Dean, who, with Barr, is co-trustee of June's fund. Barr and June fall in love and become engaged.
Meanwhile, the shipyard is the victim of sabotage, when unidentified men place explosives in the hull of the unfinished ship. After a press conference about the explosion, Barr is approached by a jounalist who has discovered that one of the men employed by Barr is a former assistant of Manning's. Barr approaches Lord Dean to ask him to accessing June's trust fund, but Dean refuses. Desparate, Barr forges Dean's signature on the document, and uses this as security on a loan from MacLoed.
Manning discovers Barr's fraud and threatens to reveal it to Dean unless Barr agrees to sell him the designs. Barr responds by revealing that Manning's role in the sabotage is soon to be public knowledge. In front of June, Manning tells Dean about the fraud.
Despite attempts to return the money, Barr is arrested and imprisoned. In the process, however, Barr's motives are revealed in the press and he becomes a public hero. Lord Dean sees the error of his opposition to Barr's plans and releases the funding to complete the first ship. Barr, on his release, is present with June for the launch.
