The League of Eyes is an organization of thief-takers and, to a lesser degree, bounty hunters. They are generally hired by victims of crimes to investigate and recover stolen goods.
The city guard of Blackbay is concerned primarily with keeping the peace and fighting any horrors that might emerge from the Barrows. While there is a limited justice system, there are very few people delegated to investigate crimes, and the higher the suspect’s social station, the higher the likelihood they will never see justice. This leaves victims of crimes with the option to hire thief-takers like those in the League of Eyes.
The League of Eyes has a reputation for honesty, and has been known to cut their prices down in exchange for promises of future favors from their clients. This network of connections may also in turn be responsible for their overall success, as they are reported to have contacts at all levels of the city, from the docks to the Basilica of St. Sabilius.
The League of Eyes also focuses on "finding lost things" for their clients. Often victims don't care about someone being brought to justice and just want their item back, but League members also have a prediliction for gathering forgotten lore and brokering information when they see fit, with an eye for having useful leads for cases that haven't even arisen yet--but will.