White lilies... Someone calling himself the Sphinx conveys murderous riddles to the intended victim in a basket with these flowers. The famous violinist Vlas Nikonov did not attach any importance to the stupid letter and paid for it with his life. Intuition told Astra Eltsova, who was investigating the murder, that the riddle had a hidden meaning. Those sentenced to death are given the chance to win a duel with the unknown Sphinx by solving it. Meanwhile, the next victim has already received an ominous message... According to legend, there is only one way to end the Sphinx: to solve its riddles. And Astra realized that this was the only way to find out who and why was hiding behind the mask of a fantastic monster...