Sea mysteries surface in the series opener, spun around a bold marine biologist who has a terrifying underwater encounter with strange creatures. So does an inquisitive teen from California and a Louisiana scuba diver, whose confrontation has a deadly outcome.

Sea creatures cause disaster on a Texas lake; Laura runs afoul of the government in her probe; Rich suffers from debilitating flashbacks; Cirko makes a startling discovery that links the beings to global warming; and Miles continues to tend to a baby creature.