Ethan Linley, a nonverbal autistic boy, is found after being presumed dead for four years. Red (James Spader) recalls the fairy tale of Lady Ambrosia, a woman who gathers unwanted children and makes them disappear. But whoever took Ethan made his disappearance look like a drowning, which leads Liz (Megan Boone) to believe it was staged with his parents' involvement. Indeed, Ethan's parents consulted with adoption agency employee Noah Shuster, who was collaborating with the elusive Lady Ambrosia to kidnap children and discreetly kill them, promising they'll turn into butterflies.
After Liz secures his trust, Ethan draws a sketch of a well with butterflies, which eventually leads the team to Lady Ambrosia's colony, a schoolhouse in the woods. A SWAT team infiltrates the scene and rescues the kids. Glen (Clark Middleton) helps Red find former KGB member Vasilia Patinka, and Red reunites her with her daughter, Anya, who was also abducted by Lady Ambrosia. In return, Vasilia hands him the Rostova file.
Hoping to learn more about Red's interest in the case, Liz asks him about her mother. Red reveals that Liz's father took her from her mother, and on the night of the fire, her parents were fighting over her. But then she accidentally shot her father, and two months later, her mother walked into the ocean and was never seen again. Red wonders if he should've raised Liz himself, and doesn't want her experiencing the same regret over her own child. But her mind is made up about the adoption, even if Tom's (Ryan Eggold) isn't.
Meanwhile, Tom's diamond heist goes wrong when Gina (Margarita Levieva) and a couple of her cronies turn on the rest of the crew. Tom takes two gunshots to the abdomen and makes a run for it. He slips into an empty home to fix himself up, but collapses and winds up in an emergency room, his fate hanging in the balance.
