Contagious picks up mere weeks after its predecessor, Infected, leaves off. Margaret Montoya, Clarence Otto and their team--now joined by the unfortunate Perry Dawsey, the only living person able to track down the infected--are still racing to figure out what the triangle infection is and how to cure it.
And the triangles themselves are mutating. We learn definitively that this is an invasion from outside our world, a colonization effort by some sort of alien species. But we still have no idea what final form the aliens will take if...when...they succeed in their efforts.
Scott Sigler is definitely honing his technique. While still jam-packed with blood, bile, charred flesh, and vomit, this book boasts a plot which is far more well-conceived and thrilling than Infected was.
And yes, there will most certainly be another installment in this series.