The Witch of Vengeance

If it weren't for these strange phone calls, Masha's friend Zoyka would be alive. They started almost two months ago. They called Masha's home number and stayed silent for a long time. Moreover, it happened when her husband, Vovka, wasn't home. Then the phone terrorist called Masha's mobile from... their home phone. And now, in her apartment, lies her best friend Zoyka in a pool of blood! How is this possible? Zoyka just wanted to check who Vovka was entertaining. Masha no longer doubted - her husband intended to drive her mad with phone calls. But he insisted: he wasn't home! So who was wandering around their rooms, who called from their home phone, and who killed her friend?..