What if aliens invaded and colonized Earth's oceans rather than its land? Britain, 1953: It begins with red dots appearing across the sky and crashing to the oceans' deeps. At first, many people believe that these aliens are interested in only what's down below. But when the polar ice-caps begin to melt, it becomes clear that these beings are not interested in sharing the Earth and that humankind might just be on the brink of extinction. . . .