A Tale of Two Cities is set during the French Revolution and mentions true historical events, such as the storming of the Bastille and the reign of terror which followed the upheaval of the monarchy, but the main story itself is fictional. The book is a classic example of a historical novel, in which fictional characters and scenarios interact with true events and settings. However, Dickens did draw inspiration from other sources when creating the story.

The love triangle at the heart of A Tale of Two Cities was not based in reality but in another fictional work. Dickens had appeared in a play called The Frozen Deep. Written by Wilkie Collins under Dickens's supervision, the play follows a love triangle between two men and a woman. The play ends with the rejected suitor, originally bent on vengeance against the man who won the woman's affections, heroically dying while rescuing his rival, even when he has the chance to kill him. Dickens was moved by the story and incorporated similar themes into the relationship between Lucie Manette, Charles Darnay, and Sydney Carton.

Lucie Manette was somewhat based on a real person, though not a historical one. Dickens gave her the appearance of Ellen Ternan, his mistress. The two had met on the set of The Frozen Deep and would continue their relationship until Dickens died in 1870.