You're right, He was the second son of Louis XVI and Marie-Antoinette, He receives the title of duke of Normandy, and becomes hear with the dead of his elder brother, Louis-Joseph-Xavier deceased on June 4, 1789.
Locked up with his family in the Tuileries, then in the Temple, after August 10, 1792, He is separated from his father on 2 December, when the lawsuit of the king opens, then of his mother on July 3, 1793. He is then entrusted to the guard of Simon a shoe-maker. This man tried to corrupt the child by teaching him a language disrespectful.
January 5, 1794, Simon gives up the post of "tutor" and the small heir, entrusted to the guard of renewed police chiefs every evening, is subjected to reinforced "safety measures".
His head was shaved, and nobody does not authorize him to see his sister, Mrs Royale, who lives solitary on the floor above. Herself speaks with a certain detachment about her small neighbor in the memories which she will write later.
The child locked up in the Temple dies abruptly in 1795. :-/
Many "false-heir" will haunt France and the world during decades which follow, of which most famous are certainly Naundorff.
Sorry for the spelling mistakes, I am not very good in English
