La otra aka The Other One (1946) Masterpiece Mexican Noir, Christmas Noir

Director Roberto Gavaldón. 

Written by Roberto Gavaldón and José Revueltas adaptation by Jack Wagner,  based on a Rian James story. The excellent cinematography was by Alex Phillips. Music by Raúl Lavista.

The film stars Dolores del Rio (Bird of Paradise (1932), Journey Into Fear (1943) as Magdalena Montes de Oca / María Méndez, Agustín Irusta as Roberto González, Víctor Junco (Bandido! (1956), as Fernando.

Also with José Baviera as Licenciado de la Fuente, Conchita Carracedo as Carmela, Carlos Villarías as Lic. Félix Mendoza, Rafael Icardo as Detective de policía, Manuel Dondé as Aguilar, policía.

The script for La otra was owned by Warner brothers. A similar Warner film about identical twins, A Stolen Life  was made the same year 1946 starring Bette Davis. The studio held onto the La otra script until they remade it in 1964 as Dead Ringer, starring again Bette Davis (she must have licked these sister roles). The Dark Mirror (1946) is similar film. This film may have influenced The Scar, aka Hollow Triumph (1948). There quite a few similarities between them also. 

Dolores del Rio as Magdalena Montes de Oca top and María Méndez bottom

Agustín Irusta as Roberto González

Víctor Junco as Fernando

A Cemetery. A big shot's funeral. Magdalena Montes de Oca. Widow. Young and now very rich. A snob. A bitch. She wears a black veil we can't see her face.  Late into this solemn tableau is Maria Méndez, Magdalena's mousey spinster-ish looking twin sister. 

Maria

Maria wears granny glasses and her hair pulled back tight. The sermons over, the gravediggers are shoveling dirt back into the hole. Magdalena scolds Maria. Tells her that she could have worn something more appropriate. 

Magdalena: Couldn’t you find something better to wear?

The funeral over. Magdalena asks her chauffer to offer her sister a ride. Maria gets into the limo and gets lectured to by Magdalena. Tells her she use her job to hook a rich man. Magdalena brings Maria to her mansion. It's the whole nine yards. Huge foyer. Grand Staircase. Statuary and fine art. 

Magdalena brings Maria to her bedroom. She flouts her wealth in Maria's face as she sheds her widows weeds. She opens her opulent closet pulls dresses off the hangers and flings them to the floor. She tells Maria she can have them. Its a back handed gesture. 

Magdalena torments Maria by telling her they are out of style anyway, and she also mentions that she was going to give one of the dresses to her maid anyway if she doesn't want them.

Maria tells her no thanks. Magdalena then walks off to the bath. Maria alone, picks up a fur piece drapes it around her neck, takes off her glasses and then sits in front of the Venetian makeup mirror. At that moment a servant opens the door. He spots Maria and tells her that the tea is ready. He has mistaken Maria for Magdalena. At that moment it all starts to go Noirsville.

Maria goes back to her menial job as a manicurist. Her boss is on her case. He wants her to be flirty with the customers. He's practically piping her out. While working the salon she keeps seeing a flashing neon sign advertising a five million peso lottery. 

Maria has a boyfriend. Roberto González. He's a cop. A detective. They love each other. He wants to marry her but hasn't asked yet because, at the pay grade he's at, he wouldn't have enough money to support her. They have a date for after work. They exchange gifts. They dine at a Chinese restaurant festooned with Christmas decorations. 

Maria lives in a rooftop hovel. When Roberto brings her home. Her landlady shows up and asks for the rent. She doesn't have it. 

She tells her landlady that she gets paid on the weekend, and that she will have to wait till then. This embarrasses Maria. Later, after their date is over and they have their goodbye kiss, Roberto leaves. Maria puts a devious plan into action. 

Maria calls Magdalena from a phone booth and tells her dramatically that she is going to commit suicide on Nochebuena (Christmas Eve) if she doesn't come to see her and talk. 

Of course, rotten to the core Magdalena, comes to see her because it affords her another delightful opportunity to demean her sister. when gets to Maria's flop house a posada procession of children crowds the stairway. Fireworks are being set off.

Maria is sitting in her robe on the bed when Magdalena arrives at her rooftop apartment. Maria tells Magdalena to sit in the rocker beside the bed. Magdalena starts her usual ridiculing but Maria pulls out a revolver from under an upside down open book. 

Magdalena hasn't a clue she thinks it's just more of Maria's drama queen antics until Maria puts a bullet in her sisters head. Part one check. Part two is to remove an already written silicide note and leave it by the nightstand.

Part three. Maria strips off Magdalena's stockings, and pulls them on her own legs. She stands, leans over Magdalena dead body and flips off her robe. She's naked underneath. 

She undresses' her sister and puts on her underwear, clothing, and jewelry. She will now be Magdalena. Part four she takes the gun and holds it into the grasp of her dead sisters hand.

When she releases the hold, the revolver drops as if from the corpse. She starts to leave going out of the door when she remembers part five. She almost left pretending to be Magdalena still wearing her glasses.

Of course it all goes deliciously Noirsille, when Maria pretending to be Magdalena finds out that the proverbial grass isn't greener on the other side.

Noirsville

One of the great Mexican Noir. There are more unforeseen challenges ahead for Maria, and some unexpected twists. If you've only seen Dolores del Río, in her Hollywood films you will be pleasantly surprised  She was cast memorably as a South Seas siren in Bird of Paradise (1932) and a leopard-skinned temptress in Journey into Fear (1943). Should be uh better known among Noiristas and Aficio-Noir-dos. Should be on Noir Alley 10/10.