London, 1666:- Thomas Farriner, a widower with two young daughters, runs a bakery in Pudding Lane and turns to administrator Samuel Pepys when naval clerk Sheridan withholds payment for the bread he has supplied to the navy. Pepys cannot help though he does inform him that his brother seems to have been lost in a sea battle against the Dutch. Profligate king Charles II, in pursuit of comely Frances Stuart, holds lavish banquets he cannot afford due to the war and is rebuked by both his brother, James the duke of York, and Pepys. Lord Denton, the king's spy-master, arrests an assassin about to murder Charles and links him to the Catholic sympathizer the Duke of Hanford. Thomas's sister-in-law Sarah works for Hanford and Denton persuades her to - reluctantly - spy for him. At the same time a spark from Thomas's oven sets alight the straw on the floor and the Great Fire of London begins.