Nancy breaks into town hall to look for a black door, but none of the doors are black. Nancy calls the Drew Crew together to figure out where to look for the door next.

Ryan gets a relic for Bess. He tells Nancy to give it to her but not to open the box until he gets there. Unfortunately, Bess opens the box, and the relic causes the Drew Crew to body swap. Nancy and Ace swap bodies. George is Bess. Bess is Nick. And Nick is George.

Nick has to go on a study date for George with a guy in her class named Cameron. Nick seems to like Cameron and tells George Cameron really likes her.

Bess has to give Nick’s speech about why he wants to run for town council. Carly, a spokesperson for Families For Truth in History, asks him if he’ll protect the town from dangerous people like Bess and the Historical Society. Bess holds her temper and says her priority is to keep the town safe.

George, as Bess, meets with a pair of brothers looking to break a curse that could destroy one of them. She brings the brothers back to The Claw, so the real Bess (in Nick’s body) can help break the curse. They put the curse in a pickle jar that must be dropped into the ocean.

Ace (in Nancy’s body) finds an arrest report that mentions a man asking to be taken to the black door, but the report is heavily redacted. The man was arrested at the Yacht Club, which has a building over 200 years old which was once used as the town’s municipal building.

Nancy, (in Ace’s body) agrees to go night fishing with Ace’s father.

Ryan gets the other half of the relic and manages to get everyone back into their own bodies.

Ace helps Nancy break into the Yacht Club after hours. There’s a banister from a 200-year-old boat, The Governance. The banister is the key to a secret passageway. There are pieces of the ship, old books, an imprint on the floor, and the corpse of a woman from the bow of the ship.

There’s also a black door with writing on it:

“I seek to put the past behind me. And I must pay, but I will find my trespass it will swallow whole this burden erased from my soul.”

Fire shows up behind the door, everything shakes, and the corpse woman turns into a monster. Nancy grabs all the books she can and runs.

Back at The Claw, Nick reads how the monster was created and that it’s called a Sin Eater. Now they have to figure out how to destroy it.

Nick wins the town council seat but turns it down. He and Bess decide to use space in his building for a satellite office for the Historical Society. If they can keep the Historical Society location on the move, then they can still help people. George agrees to help too.

George decides to go on a real date with Cameron.

Ryan realizes he got the relic from the Glasses.

It’s been one year since Kate Drew died. Since Kate loved a full house, Carson suggests having all of their friends over to remember her. But Nancy feels like they’d all be there to pity her. She just wants it to be a normal day and to mark the occasion along with Carson.

With Nancy’s encouragement to make memories while he can, Ace goes night fishing with his father. He also dumps the pickle jar with the curse in it overboard.

Spending the day as Ace, she realizes that she needs to share the good memories of her mother. She invites everyone to her house, and she and Carson share one of Kate’s traditions—a cake fight.

Later, Ace calls Nancy, and they agree that they are better in one another’s lives, even if it hurts.