Orphan Black #2

One. Of a kind. When Sarah attempted to assume the identity of a lookalike stranger, she soon uncovered an earth-shattering secret: she is a clone. Sarah also learns that someone is trying to kill them all, one by one. That someone is another clone, Helena, a murderous, self-abusing fundamentalist who believes she is the "original" and all her other sisters are "abominations" to be eradicated.