Rather than move into another hotel, Dr. Stevenson, aka Jack the Ripper, has taken up residence in a beautiful NYC apartment where the male occupant's clothing is "a little snug but otherwise a nice fit" and the modern appliances aren't too hard to figure out. Having already dispatched the female roommate, he greets the owner of the clothing he's wearing when he returns and then kills him too before returning to the kitchen to finish his breakfast burrito.
Meanwhile, H.G. is working to get the time machine back into operational order. Vanessa and Jane both do what they can to help as well as learning some things about the machine and how it works. H.G. points out the alexandrite gemstone which he says is the "very heart and soul" of the machine. Stevenson calls and demands the machine and the key to control it. He doesn't believe Wells' claims that it's broken and gives his old friend twelve hours to deliver both the operational machine and key to him or he'll kill again. As Stevenson leaves the apartment building, he is followed by the red-headed goon who was stalking him at the pub in the last episode.
Vanessa introduces Martin Scott to Wells to assist him in repairing the time machine. Scott's areas of expertise include theoretical physics and quantum physics and he's a huge fan of Wells' work, especially the stuff Wells hasn't actually written yet. H.G. explains that he wants to program the machine to return to the ballroom even if the user has the key.
Vanessa and Griffin have a campaign interview where it is revealed that the two aren't yet married despite their two-year relationship and that Vanessa's philanthropic work has been done with a very low, rather mysterious, profile. Unfortunately, the interview is interrupted when the machine malfunctions in the ballroom, and Vanessa abandons Griffin to investigate. The malfunction cracks the alexandrite and H.G. despairs at finding a replacement. Jane remembers she knows a gemologist who might be able to help.
While Stevenson is in an open-air market, he realizes that he's being followed by the goon and evades him only to bump into another red-head, this one female and named Brooke. She, a neuropathologist, simultaneously admires and scoffs at him and they end up having drinks and discussing the nature of surgeons and surgery. Despite his promised murder deadline, he can't resist spending more time with Brooke, seeing her as both a dalliance and a victim.
The goon goes to visit his mother who seems, at first, to be suffering from dementia. He has to remind her that he's her son, Chad, and that he snuck in to see her because her care-giver, Sam, can't know that he's been there. He tells her that H.G., the Ripper, and the time machine are all in New York. She becomes suddenly lucid and insists that he make sure that they don't return to Victorian London. "You can stop this all from happening," she says emphatically before she collapses in a coughing fit.
Vanessa and Griffin have an argument about her leaving the interview and he pushes her to explain what is going on with "George" and her strange distractedness lately. She pleads with him to trust her. He lets her know that her actions don't reassure him.
Wells and Jane have an intense discussion about his guilt about bringing Stevenson to New York and his belief that time travel should be only for observation. Jane argues that Fate has had a hand in what has happened and that they were always meant to meet. Wells expresses his deep appreciation and affection for her only to be interrupted by a message from the gemologist she had contacted.
Vanessa's security guy, Doug, drives them to the Gemology Institute to meet with Jane's friend, Paul. Chad follows them and breaks in through a different door. Paul spends most of their time flirting with Jane but does produce some gemstones that may be viable replacements for the time machine mechanism. While Paul is out of the room, Wells and Jane discuss physical chemistry and past relationships. Paul returns with a perfect alexandrite specimen, much to Wells' delight. When he steps out for the paperwork, Chad knocks him out, alerting Wells and Jane by the noise and a chase through the archives ensues which ends with Doug shooting Chad in the back.
Back at the Anders mansion, Vanessa has finally shared the information about Wells and the time machine with Griffin who can't believe her at first. When he realizes that she's serious, he figures that "George" is conning her somehow. Vanessa is adamant that she's doing the right thing and can get him to believe too. When Wells and Jane return, Vanessa makes a few calls, secures Paul's silence and cooperation and assures them that they'll figure out what's going on when Chad's body is identified. The gemstone is installed once Martin lets them know that he thinks the machine is ready for another test run. Before they can get started though, Vanessa enters the ballroom with Griffin so that he can witness the machine in action. The test run works, with the new programming set so that Stevenson will be trapped once he's in the machine because it'll only return him to the ballroom.
Stevenson and Brooke are enjoying their afterglow when he gets up to make a drink. She invites him to stay the night and he acquiesces. While making his nightcap, he prepares to kill Brooke and even sets up his phone to record the event so he can send it to Wells. Turning up some music brings Brooke out of the bedroom but before Stevenson can get his knife in play, she sticks him with a syringe and knocks him out, revealing she's been waiting for him to make a move.
Waiting for Stevenson to call, Wells and Jane debrief Chad's attack and share a rare and special and precious first kiss with the time machine's "thermeotic emission of electrons" shooting sparks in the background.
Out on the street, Griffin is speaking to some unknown conspirator on his cel and reveals he'd played Vanessa to get access to the time machine. He expresses concern that someone else knows about Wells and the time machine. Meanwhile, Stevenson wakes up in a laboratory, strapped securely to a table. Brooke explains that she's been waiting a very long time to meet him.