The main characters of the series "Echo" are identical twins Leni and Gina. Since childhood, even their own mother couldn't tell one girl apart from the other. Taking advantage of this, they started switching places as a prank during exams at school or when meeting friends. However, the game went on for too long and spilled over into their adult lives. Now, the sisters have two homes, two husbands, and one child between them. And none of their relatives suspect that the women are still swapping places. This continues until one of the sisters suddenly disappears.