Who, and for what reason, needed to calmly and carefully remove four young women who had been friends since their early years? One of them dies at a festive table, poisoned by mushrooms. Another burns alive in her own apartment. The third miraculously survives a terrible accident, and the fourth begins to be pursued by a maniac-killer… Who is behind all this? Where to look for his trail—in today’s day or in the distant past, when this “fourth” lived by the rules of parachute sport, and for them the most important thing was the thirst for risk and dangerous jumps?…