Claudia won't give up the bone about her sister, Claire, still being alive, and she's just discovered that the details of the case: it was a Warehouse investigation. Instead of having her chase after the mystery on her own, Artie decides to tell her the full story. Of course, that's gonna involve an artifact - namely, the very same baby booties that Pete and Jane used to access memories a few years back. Artie takes Claudia into his memories of Claire - first, when she floated above the ground, creating a tornado and throwing heavy objects with her mind, then later when their parents tried to take Claire to an expert to have her evaluated. She threw them into the car and smashed the car against the tree rather than go with them.
But the strongest memory of all is when Artie and Claudia see the Artie from that time go into Claudia's house, where a tiny Claudia sat scared and afraid, knowing that the music box (Frances Farmer's music box, according to Artie) made Claire do these terrible things. He and Mrs. Frederic see that she is a very special girl, and note that they must keep an eye on her. The music box sits smoldering in the fireplace, unable to be neutralized to save Claire.
Pete and Myka are in Washington, D.C., where a lobbyist dropped dead in a health club, spewing gallons of salty water. The man was a proponent of hydrofracking, so the duo's first thought is that an environmental group might be responsible, especially after a second pro-fraking man, Senator Wilton, falls to the same fate. But when a third victim, totally apolitical, drowns in his dry home. Now they're left with no through-line, and to make matters more complicated, their old Secret Service buddies, Ted and Elise, are also on the case due to the elected official-element. An artifact is on its way to them that will counter the effects of the drowning, but Pete and Myks will have to use it surreptitiously, if they want to keep the Warehouse a secret.
Ted and Elise have some secrets of their own, however: they've been dating after years of being partners, and just that day had a quiet wedding at City Hall. Later in the investigation, Ted talks to Pete about the sparks between him and Myka, while Elise covers the same subject with Myka. Though each partner denies any attraction, some wheels start to turn. But they don't have long to linger on affairs of the heart, because they make a connection that ties the three victims to a political scandal where a politician was seen with his intern, an affair that led to the ruination of said politician's life, and his eventual suicide.
They realize the reporter who broke the story might also be in danger, and sure enough, when they question her, she starts spewing water. Myka whips out the artifact - a silver necklace from the driest place on Earth - and she's safe for now. The partners deduce that the artifact causing this mayhem must be connected to lying. Myka weaves a quick yarn about a truth serum being the cause of a neurologically toxic response, and asks the reporter if she'd like to try a different tactic. She reports that she was bribed by Wilton's chief of staff, Diane Hewlett, to break a false story about the former senator.
The four agents investigate Wilton's office, but Hewlett, in a moment alone with Ted, flashes light off of a broken sword's hilt into his eyes. The minute he fibs to his sweetie about not ogling girls at their last investigation site, he coughs up water. Myka is on hand with the necklace, but in the confusion, Hewlett got away. They realize she's after the girl from the article, Julia Helmsworth, and they arrive at her house just in time to see Hewlett come after her with the artifact, the hilt of the sword of Alfred Dreyfuss, a soldier falsely accused of spying and subsequently imprisoned on a remote island.
Hewlett sees them coming and locks herself in a small room and shines the hilt's light into her own eyes, then says, "I'm innocent." Pete busts down the door and they bag the artifact just in time to save Hewlett from drowning herself.
Seeing the artifact partly burned makes Claudia wonder if it was she who, at a young age, threw it in the fire in a misguided attempt to save her sister, and since no one was there to see what happened, she must ask Claire. Artie reluctantly takes Claudia to see her sister, who's in an artifact-induced coma - the only way to keep her from tearing apart herself and others whenever fits of anger made her into a wind-wielding murderer. Claudia appeals to her comatose sister to help her by bringing her to memories of the music box, and with her tiniest shreds of strength, she does so. With Artie monitoring vital signs, Claudia and Jinks enter Claire's memories, first of the day Claire found the music box (Claudia saw its curse from the start) and later on the day when her parents were killed. It was Claire, not Claudia, who threw the music box into the fire.
Claire sacrificed her strength to help Claudia enter her memories, strengthening the sisterly bond between them. At this point, there is no way Claudia can leave her sister to live the rest of her life in a coma - no matter what Artie says.