It's the sweltering summer of 1776, and the Continental Congress is in a heated debate in Philadelphia. John Adams of Massachusetts is frustrated by the congress's inertia and advocates vehemently for American independence from Great Britain. His obnoxious and disliked disposition, however, impedes his efforts. Adams teams up with the more congenial Benjamin Franklin of Pennsylvania and the young and idealistic Thomas Jefferson of Virginia. Together, they push for a resolution on independence, despite the strong opposition from John Dickinson of Pennsylvania, who believes in reconciliation with England. This factional dispute threatens to fracture the nascent coalition of colonies as external pressure mounts and internal turmoil simmers.

Amidst political manoeuvring, Adams tasks Jefferson with drafting a declaration that will outline the case for separation. The soaring summer heat mirrors the rising tensions and ideological clashes among the men, as they wrestle with the weighty decision that lies before them. Personal sacrifices and the burden of shaping history are keenly felt, particularly by Jefferson, who struggles with the assignment while missing his wife. The fate of a nation hangs in the balance as principles collide with political realities, each man needing to confront and reconcile his private convictions with the public cause of liberty and nationhood.