Vincenzo Peruggia, a former employee of the Louvre, walked into the Louvre museum in Paris, walked straight up to Leonardo da Vinci's Mona Lisa, took it off the wall, hid it under his clothing and walked out, unchallenged. The painting was apparently only discovered missing when an amateur painter set up his easel and noticed there was a gap where the Mona Lisa used to be... He notified the guards.

Paris was awash with rumors, including speculation that the Germans had stolen it to embarrass the nation.

The police investigated for two years, but found nothing.

In November 1913 an Italian art dealer, Alfredo Geri, received a letter from Peruggia who told him the Mona Lisa was in Florence and demanded a ransom. Peruggia was arrested when he came to collect the money. The painting had not been damaged.

Peruggia claimed that he had taken the painting to avenge Italy of the atrocities committed by France in the Napoleonic wars. He was sentenced to a year in prison, and served 7 months.