Three inseparable friends get together every afternoon to play, but Leocádia, their evil building manager, always gets in their way. When something fishy happens around the building, they become the Blue Building Detectives!

What began as a playful project alongside the soap opera "Goede Tijden, Slechte Tijden" (Good Times, Bad Times) suddenly became deadly serious: "Ademnood" (Ademnood) topped the charts, followed by five singles, an album, sold-out performances, and a frenzy that even surprised the girl group itself. But behind all the success was something else. The series shows how young Katja, Babette, and Guusje...