The story of Eileen and Sean O'Casey has much romantic magic to it: she was a beautiful young actress working in New York when she read Juno and the Paycock and first heard of Sean O'Casey, whose career was just getting off the ground. Determined to meet the playwright, she headed back to England, got herself introduced to Sean, and about a year later became Mrs. O'Casey. They were an odd match - Sean was a 46-year-old Protestant from the Dublin slums and Eileen, who had been raised in England, was the child of very troubled Irish Catholic parents - yet their marriage lasted nearly 40 years and survived some difficult tests: an abortion Eileen underwent after becoming pregnant by an ex-lover, the death at twenty of their son Niall; the demanding presence of Eileen's old and cranky mother, years of bitterness and financial hardship after Sean's estrangement from Yeats and the Abbey Theatre. Eileen O'Casey, who knows how to be moving without being sentimental, is never evasive about her life with Sean.

This new memoir, along with her earlier volume Sean, comprises the history of her marriage. But Eileen is no competition for Sean. The new book repeats much of the information in Sean, but without the impressive style and fullness of the first book. It is, however, a useful and readable complement to Sean. (St. Martin's, $8.95)