A series of adventure novels united by a single main character - the secret organization Sigma, which takes on impossible tasks over and over again. But, after going through a series of dizzying adventures, chases, shootouts, he emerges victorious. Twenty years ago, the English archaeologist and millionaire Reginald Kensington disappeared without a trace in the legendary city of Ubar, lost in the Arabian desert. After a mysterious explosion in the gallery founded by Kensington, where treasures from Ubar are collected, scientists discover inside a stone sculpture, split in the explosion, a strange metal part - an exact copy of a human heart. The daughter of an archaeologist sets up a scientific expedition to penetrate the secrets kept by the desert. However, this explosion attracts the attention not only of scientists, but also of an international criminal group seeking to take possession of some mysterious force hidden somewhere in the dungeons of Ubar... / A mass murder occurs in the Cologne Cathedral during a festive service: all parishioners die a painful death . Criminals dressed in monastic robes steal a priceless relic that has been kept in the cathedral since the 12th century - the bones of the biblical Magi. A group of special agents from the secret organization Sigma, led by Gray Pierce, was sent from Washington to investigate the crime. Together with Vatican scientists, the group manages to establish that the Imperial Order of the Dragon, a secret brotherhood of alchemists whose roots go back centuries, is involved in the murder and abduction... Contents: 1. Sand Devil (Translation: Sergey Saksin)2. Bones of the Magi (Translation: A. Novikova)3. Black Order (Translation: Irina Charomskaya)4. Seal of Judas (Translation: S Saksin)5. The Last Oracle (Translation: A. Novikov)6. Key of Doomsday (Translation: S. Saksin)