Superman, Batman, The X-Men, Flash, Spider Man . . . they protect us from evildoers, defend truth and justice, and, occasionally, save our planet from certain doom. Yet, how much do we understand about their powers? In this engaging yet serious work, Lois Gresh and Robert Weinberg attempt to answer that question once and for all. From X-ray vision to psychokinesis, invisibility to lightspeed locomotion, they take a hard, scientific look at the powers possessed by all of our most revered superheroes, and a few of the lesser ones, in an attempt to sort fact from fantasy. In the process, they unearth some shocking truths that will unsettle, alarm, and even terrify all but the most fiendish of supervillains.