The “two cities” are London and Paris before and during the French Revolution and its bloody aftermath. This was the age of hungry peasants revolting, Europe aghast at the execution of the French royal family, and, finally, the revolution turning on itself. In the end, a seamstress who had done nothing more than sew for nobles is to be executed along with one of the nobles, who actually was a friend to the downtrodden.
As the musical paints this large canvas, in the details we find Lucie Manette fleeing France with her father after he is released from a long, unjust imprisonment. She finds love with Charles Darnay, a French aristocrat fleeing any connection with his cruel, tyrannical uncle. And there is Sydney Carton a cynical, dissolute attorney, who also falls for Lucie.
With a lot of intrigue on the French revolutionaries and many members of the serving class who provide comedy and integrity in equal measure. Again, if you don’t know the ending, I won’t spoil it, but I will say it involves heroism, redemption, a guillotine, and a very famous line. So if you want it, go get it.