Star Trek: Discovery has already made significant use of some characters from Star Trek: The Original Series, including Sarek and Harry Mudd, but did it secretly introduce another Star Trek: The Original Series character?
As the theory goes, Admiral Katrina Cornwell, played by Jayne Brook on Star Trek: Discovery, is actually the same character known as Lethe, played by Susanne Wasson in the Star Trek: The Original Series episode “Dagger of the Mind.”
Star Trek: Discovery takes place roughly a decade prior to the events of Star Trek: The Original Series. This theory suggests that the events that befall Cornwell in Star Trek: Discovery result in her becoming Lethe in Star Trek: The Original Series.
Lethe was a former inmate who was working as a therapist at a Federation of Planets penal colony. She also seemed to suffer from memory loss or confusion. When Captain Kirk asked her about what it was she did that led to her being sent to the penal colony in the first place, she replied by saying, “Does it matter? That person no longer exists.”
The name “Lethe” is appropriate since, in Greek mythology, it is also the name of a river in Hades that washes away memories. “Lethe” is also the name of an episode of Star Trek: Discovery in which Cornwell factored prominently. The episode’s title and the events of that episode are largely responsible for leading some fans to wonder if Cornwell is connected to Lethe.
From her conversations with Captain Lorca, those who have been following Star Trek: Discovery will know that Cornwell started her career as a therapist, the very same position that Lethe finds herself in “Dagger of the Mind.” So then how does Cornwell go from admiral to inmate?
It may have to do with how the “Lethe” episode of Star Trek: Discovery ended. In trying to complete Ambassador Sarek’s diplomatic mission, Cornwell was captured by Kol and is now a prisoner of the Klingon Empire.
Since Star Trek: Discovery is a prequel, we know that the current Federation-Klingon War will eventually end. That likely means that an exchange of prisoners will take place, and Cornwell would be among those prisoners if she’s not rescued during the war.
The Star Trek: Discovery episode “Choose Your Pain” made it clear that the Klingons are fond of psychological torture. The Star Trek: The Original Series episode “Errand of Mercy” revealed that the Klingons have some pretty direct means of inflicting that torture.
In "Errand of Mercy," Commander Kor - who belongs to the same house as Kol, the current leader of the Klingon Empire on Star Trek: Discovery – employed a device formally known as a mind scanner, but also referred to as a mind-sifter or mind-ripper. The device is meant to be used to dive directly into another being’s mind and find the truth without the use of drugs or other devices, but if it is applied with enough force it can cause significant mental damage.
In the episode, Spock is able to withstand the mind scanner, but Spock is half-Vulcan. Would Admiral Cornwell, who is fully human, be able to survive such torture without permanent damage?
Following this theory, the idea is that Cornwell eventually returns to the Federation, but is so mentally damaged that she needs to be placed under the care of the asylum on Tantalus V, as seen in “Dagger of the Mind.” There, her treatment causes her to forget her torture and most of her life before that.
The only thing that doesn’t quite fit is how Lethe describes her former self in “Dagger of the Mind,” saying that she was a different person who was “malignant” and “hateful.” That doesn’t fit what we know of Cornwell. Perhaps these words are leftover from what she’s told by the Klingons during her torture.
Then again, before being captured, Cornwell threatened to take command of the USS Discovery away from Captain Lorca. Perhaps calling Cornwell malignant and hateful is some last curse Lorca hurls at Cornwell whenever he next sees her, something that sticks in her mind even after the reconditioning therapy takes place.
Fans may find out more in this Sunday’s episode of Star Trek: Discovery, “Si Vis Pacem, Para Bellum,” which follows up on Cornwell’s story for the first time since “Lethe.” The episode preview certainly suggests that she is about to experience some Klingon interrogation.
New Star Trek: Discovery episodes become available to stream Sundays at 8:30 p.m. ET on CBS All Access.