Four newly elected MPs take their seats in the government: Andrew Fraser, Scottish Labour member, whose father was a Conservative MP; Raymond Gould, middle class lawyer and Labour representative; Charles Seymour, wealthy Conservative with a chip on his shoulder; and Simon Kerslake, ambitious Tory and longstanding Seymour rival.
The Labour party retains power after the general election, and the four MPs get promoted up the political ladder. However, private turmoil disrupts the careers of three of them. Charles is arrested for drunk driving, Raymond engages a prostitute with potentially ruinous results, and Andrew and his wife endure personal heartbreak.
Raymond puts his career on the line when he insists the government will not devalue the pound. Simon confronts Raymond about the economic rumors and gets offered a post that rankles Charles. Charles, in turn, is invited to become a Whip but would need to give up his privileged bank job.
Simon is appointed to a high position in the new Conservative government, but changing boundary divisions imperil his seat. Charles does everything within his power to ensure Simon loses his place, while further advancing his own interests.
The four MPs face shifting personal and political climates. Charles ruthlessly bargains for a spot on the board of his family's bank while also repairing his marriage. With the government changeover, Simon must leave Westminster and nears bankruptcy. Andrew fights against Scottish nationalists for his seat. And Raymond becomes a member of the Queen's Counsel but alienates his wife.
The Labour party wins the general election, and Simon accepts an offer to be the opposition's minister for education. However, Charles plots to bring financial ruin to the Kerslakes. Raymond and Andrew also receive ministerial appointments, but the Frasers soon suffer a devastating loss.
Marital strife envelops two of the members, as Charles discovers his wife's infidelity and Raymond's wife meets his mistress. In the political realm, Simon's streak of success continues. With the Tories back in power, he is appointed secretary of state for Northern Ireland.
Simon endures constant surveillance and threats to his life in Northern Ireland. Andrew experiences drama of his own as changes within his party threaten his political future. Meanwhile, Raymond attempts to reconcile with Joyce, and Charles learns his new wife is less than desirable.
When Libyan dissidents capture a British navy vessel, the government scrambles to find a solution to the crisis. As foreign secretary, Charles champions a diplomatic approach; Simon, the defense minister, opts for a more dangerous but decisive military course. Raymond's inquiry into the event earns him notice, and Andrew ascends to the leadership of the Social Democratic Party.
Simon and Charles battle to be leader of the Conservative party, but one of them suffers a blow that changes his perspective on politics. A general election is called and two of the MPs are in the running for prime minister - with the third holding the deciding vote.