Final answer:
Sydney Carton saves Charles Darnay from execution by substituting himself in prison due to their resemblance, in a redemptive act of love towards Lucie Manette.
Step-by-step explanation:
The question refers to Sydney Carton's plan in Charles Dickens's novel, A Tale of Two Cities, to save Charles Darnay from execution during the French Revolution. Carton's plan involves a self-sacrificial act where he uses his remarkable resemblance to Darnay to switch places with him in prison, allowing Darnay to escape the grim fate of the guillotine. This ultimate act of redemption ensures that Lucie Manette, whom Carton loves, will not lose her husband, and it exemplifies the theme of resurrection that permeates the novel.