The H.E.R.O. series continues with its fourth novel. Aliens come to the Sol system to research the umbra - or dark energy behind the powers of supers both on Earth and elsewhere. Finding Earth unexpectedly populated, and after being attacked by another alien vessel, their starship is forced to land near Metrocity. The scientists decide to investigate some of the superhuman activity in the city while repairs are made upon their starship. Separately, researcher Cam Huntsbury leads a team in ongoing research on the meteorite involved in the mutation of humans into supers. An experiment goes...