Two calls, one from Artie asking for help finding the source of a tremor in the Warehouse, and one from Helena Wells, of all people, interrupt a mediocre breakfast. In her new life as Emily Lake, forensic scientist, in Wisconsin, Helena encounters a man who turns himself in for murder, and physically transforms before her eyes. When Myka and Pete arrive, she gives them as much information as she has, then exits the investigation.
In the warehouse, Claudia is avoiding the gaze of Dr. Abigail Cho and hoping that nobody notices that the Warehouse keeps zapping her behind - she thinks that the building is mad at her for stabbing Artie and doesn't want the good doctor, who's new to the peculiarities of Warehouse life, to think that's she's completely cuckoo. They finally pinpoint the source of the tremors in the Yukon sector, which houses the railroad tie that binds things together. The warehouse, which - surprise! - automatically expands to fit the increasing number of artifacts, is trying to do its job but is stopped by the railroad tie.
Claudia and Steve create a "ba-goo-ka" that will deliver a missile of goo directly on the expanding joint and relieve the pressure, but while Steve aims the thing, another tremor hits, breaking the ladder he's on and injuring Artie. With those two out of commission, Claudia and her nemesis-for-now press forward. Abigail finally drags the truth out of Claudia: she's afraid that if the Warehouse is mad at her and that she won't get to be Caretaker, but Abigail suggests that her special relationship with the building means that it was trying to get Claudia's attention. Claudia's encouraged and walks into the center of the electrical storm like it's nothing, blasts the ba-goo-ka and saves the day. Also, she and Abigail can now be friends.
When Pete and Myka talk to the transformed man, he says he doesn't quite know why he confessed, but tells them definitely that the other man suspected of the killing is absolutely innocent, and whatever happened before he came to the police station is too horrible to remember. Myka begs H.G. for her help getting surveillance videos from the police station, and when she finally relents, they find that a Detective Briggs knew the man would be in soon, and was waiting and ready.
Helena's involvement brings just what she was afraid of, for soon Briggs arrives at her home and uses the artifact - a prehistoric hyena jawbone - on Helena's boyfriend, Nate. They manage to bag it before it turns him into a caveman and kills him, but Briggs gets away and goes after Nate's daughter, Adelaide. He tells "Emily" to bring the bone to him if she wants to see Adelaide again. Myka, wracked with guilt over involving others, goes after Briggs, herself, but Helena and Pete show up just in time, for Briggs isn't working alone! The D.A. is also in on the conspiracy, and the downside of the artifact has him locked in permanent rage. They use this to their advantage and slap cuffs on them while Helena rescues Adelaide.
Myka and Pete return the women to a relieved Nate, and gain Helena's promise that she will make the most out of her happy life, and do her best never to need them again. They both want to believe that there's a better future possible for Warehouse agents than what they've seen.