Night Watch

A graffiti artist kidnaps babies that remind her of her own baby who died because she wasn't paying attention to him.

Tropes in this episode

Disposable Fiancé: Lewis dumps her fiancé in his very first episode.
Grief-Induced Split: The episode revolves around a couple who split after their young son wandered away from his mother and drowned.
Murder-Suicide: What the UnSub does in the end: He jumps down a roof and pulls his ex with him.
Samus Is a Girl: Morpheus, though the masculine form of the name of a Roman god, is the alias of a woman named Ellen.