The fourth season of "Once Upon a Time" has introduced a series of improvements and additions, including the characters from "Frozen" as well as three Queens of Darkness. Episode 16 titled "Poor Unfortunate Souls" appears it will follow suit by diving into the history of Ursula and Hook. 

According to TVLine, the next episode will have an elaborate flashback sequence that will show the origin of Ursula and what Captain Hook has done to her. According to Eddy Kitsis, co-creator of the series, Hook's actions go beyond a simple heartbreak. 

He commented, "When you think about what would be worse than having your heart broken, I would say having your soul crushed." 

The synopsis of the episode indicates that the young Ursula attempted to run away from her home and enlisted Captain Hook to help her, only to discover that trusting a pirate was the worst thing she could do. 

In the present day, Hook will be using this painful backstory to learn from Ursula what Gold is really up to and why he desired to bring Maleficent back to life. 

Ursula and Hook won't be the only focus of the episode. The synopsis also indicates that the Queens of Darkness and Gold will be pushing August to the limits to learn more about the Author. David, Emma, and Mary Margaret (Snow White) attempt to find them and save August. 

Hook has been a protagonist on the show for so long that fans may have forgotten he was once a tried-and-true villain. "Poor Unfortunate Souls" is set to remedy that by revealing his dark past with Ursula. It will also play into Gold's scheme involving Maleficent and Emma. 

"Poor Unfortunate Souls" is set to air on March 22. It is directed by Steve Pearlman and penned by Andrew Chambliss and Dana Horgan.