The Shadow Thieves are a thieves guild based in the city of Athkatla, a large port city. They were the original Thieves guild of Waterdeep, until they were driven out and to Amn by the Lords of that city. It is alleged they have some arrangement with the Council of Six, as the merchants of Waterdeep are the main trading enemies of Amn.
Although based in the port city of Athkatla (in the nation of Amn), they are said to sponsor a number of criminal activities in other cities including Baldur's Gate.
One of the leaders of the Shadow Thieves is known as Nards, founder of the Nards Collective - a sub group responsible for all manners of manipulation. Nards has been loosely linked with many types of criminal and less than ethical activities including political manipulations, black mail, and prostitution. The Nards Collective is unique among similar organizations because the gender of its members is never revealed. However, a few clues are given. A female Nards member may have been a madam responsible for the operation of brothels and street-walkers in several locales. A male Nards member may have acted as a surrogate father-figure for several street urchins, who later formed the Collective.