In the summer of 1885, three Frenchmen arrived in London for a few days' shopping. One was a Prince, one was a Count, and the third was a commoner, who four years earlier had been the subject of one of John Singer Sargent's greatest portraits. The commoner was Samuel Pozzi, society doctor, pioneer gynaecologist and free-thinker - a scientific man with a famously complicated private life. Pozzi's life played out against the backdrop of the Parisian Belle Epoque. The beautiful age of glamour and pleasure more often showed its ugly side: hysterical, narcissistic, decadent and violent, with more parallels to our own age than we might imagine.