During the month of June, an eight-year-old Red Riding Hood listens intently while her grandmother Granny recounts to her the tale of how Lake Nostos came to be. According to the storybook from whence Granny reads from, there used to be an exquisite castle located deep within the Enchanted Forest ruled by a King and Queen Nostos. Every morning the king would enjoy travelling to a nearby spring. One day, the queen decided to surprise him for his birthday. Upon arrival at the spring however, she saw how the king was listening to a fair washerwoman who had a beautiful singing voice. After she finished with the clothes, she would dress down and jump into the water. Seeing that the king's attention was focused on the woman's beauty, the queen feared that he now loved the washerwoman more. The queen then turned to an evil sorceress in the hopes of placing a curse upon the washerwoman. The next morning, the washerwoman was unable to leave the water after jumping in for a swim. She could no longer breathe out of water. Sometime later, the washerwoman grew powerful in her new domain, expanding the spring into a lake. Determined to get her revenge, she was finally able to cause the castle to be pulled whole into the lake. The lake was then said to be able to cure curses. 
Prince Charming travels to this lake to retrieve some of its water for Princess Abigail because her true love, Frederick was accidentally turned into a golden statue by her father, King Midas, whose touch turns anything into gold. Legend has it the waters of Lake Nostos in the Enchanted Forest can restore life to someone who is cursed. Prince Charming successfully gathers the water after killing the guardian of the lake, the Siren, when she tried to lure him to his death. Abigail uses the waters to revive Frederick back to life. ("What Happened to Frederick")
After Prince Charming and Snow White plan to take back the kingdom from King George and the Evil Queen, their journey is sidetracked after Prince Charming's mother, Ruth is severely injured during an attack and struck with a poisoned arrow by one of King George's men. Lancelot, who left the service of King George and joins the party, goes to the lake seeking out its waters to get some for Prince Charming's dying mother. Unfortunately, the lake has all but dried up since the Siren has been killed. Lancelot finds a few drops of the lake's water left, but Ruth is reluctant to drink it after learning the king has cursed Snow White to become barren. Knowing the water can cure the princess, Ruth secretly switches it out to Lancelot. As Ruth is near death, she asks to see her son and his love be married. During the ceremony, Lancelot pours the lake's water into a cup that is thought to have mystical properties of granting eternal life. Snow White drinks it and is healed of her barrenness, though she doesn't yet know. Soon after they are married, Ruth perishes. Afterwards, when Prince Charming attempts to use his mother's old necklace, which has the power to determine the gender of a woman's first-born child, on Snow White, she is shocked to see the pendant works. Only then, she realizes the truth extent of Ruth's sacrifice for her. ("Lady of the Lake")
Emma and Mary Margaret become trapped in the Enchanted Forest after they are accidentally transported there by the use of a hat. They team up with Mulan and Aurora, and for a brief time, Hook, to find a way back to Storybrooke. Emma is given an enchanted compass by a giant that will help them return home. After Aurora is kidnapped by Cora and returns unharmed, they continue on their journey, but become trapped in Rumplestiltskin's old jail cell. They free themselves in time to reach Lake Nostos as Cora uses magic to restore the water of lake, at least partially, and Hook pours the ashes of the magic wardrobe into it to create a portal to Storybrooke. Emma, Mary Margaret, and Mulan stop her and Hook from going through after a battle. Mulan hurries off to restore Aurora with her heart after Hook gives it back. Cora makes an attempt to tear out Emma's heart, but is blasted back by a light coming from inside Emma's body. Then, Emma and Mary Margaret jump into the open portal homeward. Cora and Hook are left in disappointment of their failure, but Hook rejuvenates the shriveled magic bean he got from the giant with the water, and uses it to get both of them to Storybrooke on his ship. ("Queen of Hearts")
- Lake Nostos is featured in the title card for "Queen of Hearts".
- "Nostos" is Ancient Greek for "homecoming". It is the root of the word "nostalgia," meaning longing for the past; fitting for magical water that can return something that was once lost. ("What Happened to Frederick", "Queen of Hearts")
Fairytales and Folklore
- The name "Nostos" is a reference to the theme used in Ancient Greek literature, a theme usually involving an epic hero who has to travel at sea and eventually succeeds in coming home. The prime example of this is seen in Homer's Odyssey, which includes among other things, the hero Homer having to overcome Sirens who tempt him to abandon his journey.
- The Makin Lands at Britannia Beach in Vancouver, British Columbia doubles as Lake Nostos in "Lady of the Lake" and "Queen of Hearts". The same area also doubles as a tunnel in Storybrooke in "Fruit of the Poisonous Tree" and "The Broken Kingdom".
- The Makin Lands also doubles as the Sector Four Tunnel in The 100 episode "Wanheda: Part 1" (a show which features Once Upon a Time guest star Jarod Joseph and Once Upon a Time in Wonderland guest star Leah Gibson), a field in Redmond in the Legends of Tomorrow episode "Invasion!", a quarry in the Siren episode "Entrapment" (an episode which features Once Upon a Time guest stars Chad Rook and David Cubitt) and a North Korean Nuclear Silos in the 2014 action comedy film The Interview (a movie which features Once Upon a Time guest star Geoff Gustafson).
|Once Upon a Time: Season One|
|"Pilot":||"The Thing You Love Most":||"Snow Falls":||"The Price of Gold":||"That Still Small Voice":||"The Shepherd":||"The Heart Is a Lonely Hunter":||"Desperate Souls":||"True North":||"7:15 A.M.":||"Fruit of the Poisonous Tree":|
|"Skin Deep":||"What Happened to Frederick":||"Dreamy":||"Red-Handed":||"Heart of Darkness":||"Hat Trick":||"The Stable Boy":||"The Return":||"The Stranger":||"An Apple Red as Blood":||"A Land Without Magic":|
|Once Upon a Time: Season Two|
|"Broken":||"We Are Both":||"Lady of the Lake":||"The Crocodile":||"The Doctor":||"Tallahassee":||"Child of the Moon":||"Into the Deep":||"Queen of Hearts":||"The Cricket Game":||"The Outsider":|
|"In the Name of the Brother":||"Tiny":||"Manhattan":||"The Queen Is Dead":||"The Miller's Daughter":||"Welcome to Storybrooke":||"Selfless, Brave and True":||"Lacey":||"The Evil Queen":||"Second Star to the Right":||"And Straight On 'Til Morning":|
|Once Upon a Time: Season Six|
|"The Savior":||"A Bitter Draught":||"The Other Shoe":||"Strange Case":||"Street Rats":||"Dark Waters":||"Heartless":||"I'll Be Your Mirror":||"Changelings":||"Wish You Were Here":||"Tougher Than the Rest":|
|"Murder Most Foul":||"Ill-Boding Patterns":||"Page 23":||"A Wondrous Place":||"Mother's Little Helper":||"Awake":||"Where Bluebirds Fly":||"The Black Fairy":||"The Song in Your Heart":||"The Final Battle Part 1":||"The Final Battle Part 2":|
|Once Upon a Time: Novels|
|Once Upon a Time: Specials|
|"Magic is Coming":||"The Price of Magic":||"Journey to Neverland":||"Wicked is Coming":||"Storybrooke Has Frozen Over":|
|"Secrets of Storybrooke":||"Dark Swan Rises":||"Evil Reigns Once More":||"The Final Battle Begins":|
Note: "Archive" denotes archive footage.