Father of the Year? (spoilers)

I tuned in late to a showing of this flick and so missed any scenes that would have explained to me why Phillipe would have endangered his own son by leaving him as a masquerading substitute for the Dauphin. And while I've enjoyed Louis Jourdan in almost anything he's acted in (world's best Dracula...why doesn't anyone remember that?) it was a pretty pifitful reaction and unbelievable rebound when he found that his son had been murdered. Any enlightenment would be appreciated.