With Emma now facing the nature of the Darkness in herself, she encounters Merida. Her family and friends go to extreme measurements to find Emma and bring her home safely.

While Prince Arthur organizes a ball in Camelot, darkness rises in Storybrooke, to the search of a savior.

In Rumplestiltskin return, Emma takes her chance at the taking of Excalibur, while King Arthur's real identity is revealed.

Gold and Merida are tested to their limits, can they be the heroes they need to be? King Arthur's help is needed to contact Merlin but can he be trusted

Emma's darkness is tested while she has an encounter with the first "dark one". The history of Excalibur is revealed.

Hook risks everything to uncover the truth about what Emma did in Camelot.

Red and Mulan return to help Merida uncover the truth about her father's death.

Hook's centuries old lust for revenge against Rumpelstiltskin is reignited. Destiny collides as the forces of light and dark are on a charged confrontation.

The dark siege of Storybrooke is underway as all of the resurrected Dark Ones target a living soul for sacrifice so that they can return to the realm of the living.

The mission to rescue Hook from the Underworld turns out to be more difficult than expected as the heroes encounter souls with unfinished business.

The heroes join forces with an old friend of Snow's to defeat an obstacle standing in the way of finding Hook. Meanwhile, Hook encounters challenges of his own.

Hook's captivity takes a dark turn when Hades threatens to condemn him to the River of Lost Souls after Hook refuses to choose which three of his friends will have to remain in the Underworld.

A surprise visit from Hook's brother Liam may provide Hook and Emma with the tools they need to defeat Hades; and in flashbacks, the bond between the Jones Brothers is tested as their merchant ships head into a storm.

Gold creates a Storybrooke portal; Zelena and Regina clash; Belle and Rumple are reunited; Snow and David try to send a message from the Underworld to their son, Neal.

Belle turns to Rumplestiltskin with hope of finding a way to protect their child from Hades. However, they disagree over whether to use dark magic, as Belle forbids Rumplestiltskin from using his powers for evil.

In flashbacks, Ruby and Mulan find themselves in Oz, where they meet Dorothy. After the three witness Zelena's return to Oz, they look for a way to defeat her once and for all. However, Dorothy mysteriously disappears.

Now that Hades and Zelena have been reunited, Hades tells Zelena about his plan to leave the underworld forever and Cora reveals information from the past that will change the lives of Regina and Zelena forever.

Hades turns to the heroes to ask for help with getting Zelena back from Rumplestiltskin and Peter Pan. In flashbacks, Emma searches for answers about her family and makes an unexpected friendship.

Regina grieves over Robin Hood's death and Henry sets out to destroy all magic.

Regina and Emma set out to find Henry before Gold does. Meanwhile, Snow, David, Hook, and Zelena are imprisoned in a strange new land.