Mistique can be found here http://www.mistique.eu/. The brand has three offerings in their collection: Romance, Elegance, and Fashion. The Romance line is very sleek and looks more Scandinavian than Polish. It can be found in simple, deep colors like creme, brown, and black. The Elegance collection is similar to the Romance collection with the addition of important details like a scalloped bust line for the bra and matching bows on the knickers.
Mistique shares a name with another Polish brand – Passon (see TLP Archives). This makes finding the brand online difficult. There is no company store and I suspect that most of the sales are through retail stores in Poland.
Photos from Mistique.