The Liverpool docks. Mr Garfield of the Ministry of Labour arrives for a meeting with the dockers' union, the unofficial port workers' committee and the port employers, in an attempt to avert strike action. The strike is a protest against the measures laid out by the recent Devlin report, which proposed mechanisation of the docks and casualisation of the workforce. The dockers fear unemployment. Despite their reassurances, the employers will not give a written guarantee of full employment to the men. Garfield also insists that their demand for increased wages are impossible due to national prices and incomes policy. The meeting ends in acrimony.

Freddie Grierson, a radical socialist, advocates revolution to the cynical and sceptical dockers.

Striking dockers claim state benefits for their wives and children, but find they cannot claim anything for themselves while striking. The dockers and their families struggle with poverty.

Six weeks into the strike, the port employers and the official dockers' union meet. They resolve to open negotiations only when the strikers return to work. The strike committee reject this proposition.

Strike leaders Peter Connor and Danny Fowler meet with the ex-Communist Jack Regan, a previous strike leader. He advises that the strike cannot be maintained indefinitely; the men will eventually have to go back to work due to economic pressures. Regan advocates workers' control of the port, imagining a Socialist utopia for working men. Connor and Fowler slowly become convinced.

With Regan now on board, the strike committee puts the proposal of workers' control to the dockers. They have arranged foreign ship owners' agreement for them to unload their ships. The strikers vote in favour of the resolution and it is put into effect.

Masses of troops arrive at the port to assist the police in maintaining order, though they profess to expect no violence. Grierson attempts to sneak into the sealed-off port to join the new system, but is arrested by police.

Fowler is called out when the skipper of a British ship refuses to allow the dockers working under the new system to unload her cargo. A third of the ships docked in the port are British and all are similarly refusing. Danny believes it's a conspiracy between the employers and the government, who hope to see their system fail.

Grierson finds himself sharing a police cell with another arrested docker, Tommy O'Neil. Tommy says that he has made contact with representatives of another industrial workers' union, who seek to meet with Regan, keen to expand the experiment of workers' control.

Released by the police, Freddie goes straight to strike committee and passes on the contact details for the union representatives. They are expecting Regan that night at a pub along the coast. Although there is some suspicion of this arrangement, the committee pass the motion that they should meet delegates. Regan and Fowler go that night by boat, but the meeting is a trap and they are intercepted by police.

With Regan and Fowler in custody, police and soldiers storm the dock gates. The dockers convene and face up to the ranks of soldiers. They are asked to disperse and go home. Peter Connor, one of the remaining strike leaders, recognises that this is the point of defeat that they had all foreseen, and that resistance would only cause senseless violence. He agrees that the dockers will concede.

Grierson, however, refuses. He recognises O'Neill in the police line and realises that he was used by the police to trap Regan and Fowler. Grierson goes for O'Neill, provoking a large-scale brawl between dockers, police and soldiers. Grierson is kicked to the ground and beaten.

Later, the strike committee are tried for conspiracy to affect a public mischief. Regan speaks passionately in their defence, but they are each sentenced to three years in prison.

The radio reports that car workers in the midlands and dockers in other major ports are striking in sympathy. At the Liverpool docks, the dockers remain defiant and a rabble-rouser leads support for the election of a new workers' committee - and if necessary another, and another...