The latest pieces from designer Mona Kowalska had an Agatha-Christie-meets-The-Parent-Trap feel: somewhat mysterious, with a hint of Victorian England that’s both vintage and youthful at the same time. At the heart of the collection was a rotating mix of tartan pieces and statement suits. Shapes were conservative—but that did not prevent the overall thrust from achieving a bookish edginess that attracts Kowalska’s cult following time and time again.