"We have a very simple rule. It's a rouble to get in, but two to get out." Thus begins the extraordinary chronicle of Viktor Suvorov's early preferment within the Soviet Army which brought him to Vienna as a spy in military intelligence and ended in his defection to the West.

Suvorov's path into espionage was a long one, and not one he chose for himself. Throughout this astonishing record of life on the General Staff of the Soviet Army, to which Suvorov was promoted after ordering his tank company to break out of the tank park by demolishing a wall, and within the elite units of sabotage troops which were his training ground before posting to the undercover residency abroad, it is clear that Suvorov had grave doubts about his entanglement with Soviet military intelligence - the GRU.

Here Suvorov reveals for the first time what life was like for those who joined "the Aquarium" - the nickname for GRU headquarters. He talks about the twenty-four hour-a-day training; the arduous fieldwork practice in the back streets of Moscow; the competition between officers abroad to avoid being sent home to disgrace, or even to the crematorium; the daily grind of spying; and the secret operations in the towns and countryside of Europe, many of which were blinds devised only to test his loyalty. The end came when Suvorov knew that he had to inform on the one man in his residency whom he admired.

Viktor Suvorov was a spy. He is now a writer. Having established himself as an international expert on the Soviet Army, he has chosen to disclose what must be the most sought-after story of all. Written in his uniquely down-to-earth way, but full of stunning - and ironic - insights, Aquarium is a sensational memoir.