S1, E1: “… all the waters that were in the river [Nile] were turned to blood. And all the fish that was in the river died,” reports the Bible, “and the river stank, and the Egyptians could not drink of the water of the river.” (Exodus 7:20–21). With water pollution and temperatures on the rise, toxic algae cause serious problems nowadays for inland waters and for the oceans. Increasing algal bloom is poisoning fish and shells, and it has become a health hazard for human beings as well: toxic algae are responsible 60,000 cases of food poisoning worldwide every year. The documentary, Return of the Plagues, takes a closer look at the effect these poisonous microorganisms have today.