Number One Becoming A Replacement Changes Star Trek’s Doppelganger Rules

Warning: SPOILERS for Star Trek: Strange New Worlds Season 4, Episode 4 - "A Case of Chiaroscuro"Commander Una Chin-Riley (Rebecca Romijn) replacing her exact double in Star Trek: Strange New Worlds changes what we know about Star Trek doppelgängers. Directed by Meera Menon and written by Skylar Ojeda and Dana Horgan, Star Trek: Strange New Worlds season 4, episode 4, is a film noir homage to Casablanca that centers on Number One.

In Star Trek: Strange New Worlds season 4, episode 4, "A Case of Chiaroscuro," Una, Dr. Joseph M'Benga (Babs Olusanmokun), and Ensign Nyota Uhura (Celia Rose Gooding) are stranded on Mat'Aar XII, a planet under Klingon occupation. The Starfleet officers must go undercover on Mat'Aar, a planet whose sun emits radiation that renders everything in black and white.

Number One is immediately mistaken for Nevette, a Klingon collaborator who works directly with Mat'Aar's Klingon governor, Commander Kor (Demore Barnes). However, Nevette is also secretly the leader of Mat'Aar's resistance. Una and Nevette are so identical that only Roman (Andy McQueen), who murdered the real Nevette, knew that the USS Enterprise's First Officer was an impostor.

Star Trek: Strange New Worlds Reveals Characters Have Unexplained Doppelgangers

How Una Chin-Riley and Nevette can be identical goes unexplained in Star Trek: Strange New Worlds season 4, episode 4. The bizarre coincidence is hand-waved away by Dr. M'Benga, who suggests to Uhura that in such a vast universe, he finds it surprising that they don't run into their doubles more often. That's all well and good, but it's a very thin rationale for Star Trek.

"A Case of Chiaroscuro" is a film noir and plays by those established tropes. Characters having identical doppelgängers is a staple of film noir, and even classic literary works. "A Tale of Two Cities" by Charles Dickens, which was lovingly referenced in Star Trek II: The Wrath of Khan, hinged on Charles Darnay and Sydney Carlton being identical.

Yet scientific (or even pseudo-scientific) rationales are expected of Star Trek, and "A Case of Chiaroscuro" sidesteps how Una and Nevette can be exactly the same. Somehow, Number One looks and even sounds exactly like Nevette and is able to easily replace the Mat'Aar resistance leader. No one besides Nevette's killer can tell any difference, not even Commander Kor.

The contrivances that "A Case of Chiaroscuro" requires audiences to accept include everyone on Mat'Aar XII speaking English (or whatever standard language is used in Star Trek), and Una and Nevette not only looking the same but also sounding exactly alike.

Thus, on this black and white world located in Klingon space, Nevette is a perfect lookalike of genetically engineered Illyrian Una Chin-Riley in every way, and Number One just happened to land on Nevette's planet and was able to impersonate her without fail.

Why Strange New Worlds Just Rewrote Star Trek’s Rules Of Exact Doubles

Star Trek characters meeting their doppelgängers is nothing new, and has been happening since Star Trek began 60 years ago. There is usually an explanation, and the most common is a transporter malfunction, starting with Captain James T. Kirk (William Shatner) being split into his good and evil sides in Star Trek: The Original Series season 1's "The Enemy Within."

A transporter accident created Commander William Riker's (Jonathan Frakes) exact double, Thomas Riker, in Star Trek: The Next Generation season 6's "Second Chances." Star Trek: Lower Decks comically repeated TNG's transporter duplication, creating Ensign Bradward Boimler's (Jack Quaid) transporter clone, William Riker.

The Romulans cloned Captain Jean-Luc Picard (Patrick Stewart) with Shinzon (Tom Hardy) in Star Trek: Nemesis. However, the easiest way for Star Trek to introduce doppelgängers is via the Multiverse. From the evil versions of Star Trek characters in the Mirror Universe, to the many other alternate timelines that exist, virtually everyone in Star Trek has a duplicate somewhere out there.

Ultimately, Star Trek: Strange New Worlds' "A Case of Chiaroscuro" didn't find it important to conjure an explanation for how Una and Nevette were identical. Instead, the episode's technobabble rationale centered on why everything was black and white. However, this also means that characters' exact doubles randomly existing is a thing now in Star Trek canon.

Star Trek: Strange New Worlds season 4's new episodes premiere Thursdays on Paramount+