Three inseparable friends – Tom, Mila and Capim in the first six seasons; Pippo, Sol and Bento from the seventh – live in a very old building, full of mysteries, deciding to unravel them in dazzling adventures. In the secret club, which is in a part of the courtyard, camouflaged and not known to adults, they wear their super-equipped cloaks and become the Blue Building Detectives.