Second solo novel (following Lincoln's Dreams, 1987) from an author best known for her strong stories (the collection Fire Watch, etc.). In the Oxford of Christmas, 2054, time travel is a well-established tool of historical research. Kivrin Engles has labored diligently to acquire the language and practical skills necessary to survive in the 14th century--for her destination is Christmas, 1320. Nearby, an archeological dig is uncovering artifacts from the same period. But problems beset the ""drop"": Kivrin's schedule is advanced by Gilehrist, the professor in charge (he's more concerned with his reputation than the safety of his researchers) before her immunizations (irritatingly called ""inoculations"" by Willis) can take full effect; and the technician in charge of the time-calculations, Badri, falls mysteriously ill just as the drop goes ahead. Dunworthy, Kivrin's academic mentor and friend, his place usurped by Gilchrist, suspects something has gone wrong--but the delirious Badri can provide only forbidding hints. Soon a full-blown influenza epidemic is raging. Meanwhile, in the 14th century, Kivrin overcomes initial obstacles (she comes down with the flu; her mental translator doesn't work) to become absorbed in the life and people of a tiny village--in particular she admires Roche, the priest, a simple and illiterate Anglo-Saxon despised by the local Norman aristocracy. But as an enigmatic ""blue sickness"" takes hold in the village, Kivrin realizes that she's not in 1320 but 1348--the year bubonic plague ravaged England. Soon, the entire village lies dying, nursed only by Kivrin and the saintly Roche, who, ironically, thinks she's a saint sent by God to restore the faith. Meantime, up in the 21st century, Badri hovers near death; Dunworthy, desperately worried about Kivrin, himself succumbs; plague dominates both centuries. Solid characters, crisp, almost perfect detail, and excellent subplots that maintain the tension at an almost unendurable level. Splendid work--brutal, gripping, and genuinely harrowing, the product of diligent research, fine writing, and well-honed instincts, that should appeal far beyond the usual science-fiction constituency.