The second installment of Turtledove's vast WW II/alien invasion saga simply picks up where Worldwar: In the Balance (1993) left off. The progress of WW II has been interrupted by alien invaders. After initial defeats, the various Earth powers are learning, often painfully, to set aside their differences and cooperate against the infinitely more dangerous Lizards. As before, Turtledove's global approach mingles historical and fictional characters while juggling more than a dozen occasionally intersecting plotlines involving, among others, panzer officers, baseball players, radarmen, female pilots, physicists, Chinese peasant women, infantrymen, and numerous Lizards. Several human groups rush to develop nuclear weapons. Ginger, to the Lizards, proves to be a euphoric, addictive drug. And 20 years hence, a second and much larger Lizard colony fleet is due to arrive on Earth. Turtledove hasn't the knack of sketching really distinctive characters, but his patiently detailed panoramic saga -- a detachment rather than an independent module -- continues to engage.