Those searching for Emma receive help from unexpected allies; Emma struggles to resist her dark urges as she tries to find Merlin before her transformation is complete.
Regina steps up in an unexpected way to protect Emma; a celebration at Camelot turns deadly; Hook tries to bring Emma back to the light.
Mary Margaret is unable to convince David that Arthur could be dangerous and decides to takes matters into her own hands; Hook's love gives Emma hope.
Chris escapes the facility as the military enter a state of high alert, but he's not the only one to make it out.
A surprise guest at Ben's mothers fundraiser offers to stop the overfishing which is jeopardising the mermaids' survival.