Describe a scene in a Tale of Two Cities in 5-6 sentences.

In the end of the story, Carton decides to do the noble thing and die in Darnay's place.  They look similar enough to change places and Carton drugs Darnay and has him sent to his family.  Darnay and his family leave the city safely as Carton goes to his death.  Carton is recognized by one of the other prisoners who asks him why he would sacrifice himself.  He says that he does it for Darnay as well as for his wife and child.