Jekyll (played by Hank Harris) is plotting to kill Belle as revenge for his love Mary's death. Belle is stuck on the Jolly Roger while Hyde (played by Sam Witwer) compels a helpless Rumple to stand by and watch the terror unfold. Luckily, Hook arrives to save the day, and Jekyll falls backward onto a harpoon. On the dock Hyde collapses, clutching a wound in the same place as Jekyll's. Gold tells Regina that now they know how to destroy one's doppelganger - by killing the original. Watch the death of Dr. Jekyll and Mr. Hyde from the Once Upon a Time Season 6, Episode 4, 'Strange Case.'