However , on examination , Paul realizes the painting has been replaced with a fake .
When Leonardo da Vinci 's Madonna and Child arrives at London 's Tate Gallery for a special exhibition , American Paul Mitchell ( Dennis O'Keefe ) is assigned to guard it .
On examination , Paul Mitchell realizes the painting has been replaced with a fake .
When Leonardo da Vinci 's Madonna and Child arrives at London 's Tate Gallery for a special exhibition , American Paul Mitchell ( Dennis O'Keefe ) is assigned to guard it .