Agrippina the Younger attained a level of power in first-century Rome unprecedented for a woman. According to ancient sources, she achieved her success by plotting against her brother, the emperor Caligula, murdering her husband, the emperor Claudius, and controlling her son, the emperor Nero, by sleeping with him. Modern scholars tend to accept this verdict. But in his dynamic biography - the first on Agrippina in English - Anthony Barrett paints a startling new picture of this influential woman.

Drawing on the latest archaeological, numismatic, and historical evidence, Barrett argues that Agrippina has been misjudged. Although she was ambitious, says Barrett, she made her way through ability and determination rather than by sexual allure, and her political contributions to her time seem to have been positive.

After Agrippina's marriage to Claudius there was a marked decline in the number of judicial executions and there was close cooperation between the Senate and the emperor; the settlement of Cologne, founded under her aegis, was a model of social harmony; and the first five years of Nero's reign, while she was still alive, were the most enlightened of his rule. According to Barrett, Agrippina's one real failing was her relationship with her son, the monster of her own making who had her murdered in horrific and violent circumstances.

Agrippina's impact was so lasting, however, that for some 150 years after her death no woman in the imperial family dared assume an assertive political role.