She was gorgeous! Look at the pictures on the second link.
Margaretha Geertruida Zelle alias Mata Hari was born in Leeuwarden (NL)
on 7 August 1876.
At the beginning of the 20th century she moved to France where she started a career as a nude dancer. She became famous and moved in the highest circles of Europe. Her fame made it easy to travel to various European countries. Even during the war. So, the French Secret Service asked Mata Hari to mingle with the Germans and find out as much as she could.
However, during her first mission something went wrong and she was arrested by the British Intelligence Service. All of her alibis were watertight, so the British agents had to release her. In the meantime, the French too got suspicious.
It also became clear that German army officers were paying her. Officially it was to keep them company but the French intelligence office wasn't so sure about that. When she tried to cross the French border, to visit one of her lovers, she was arrested by the French Secret Service and interrogated.
During one of these long sessions, she succumbed and confessed to be a German spy, known under the pseudonym of H21.
The trial that followed was nothing but a showcase. The French were convinced that she was: "one of the greatest spies of the century, responsible for the death of tens of thousands of soldiers". She was found guilty and condemned to death. On 15 October 1917 she was shot by a firing squad.