Summary
Walter leaves the Dietrichson residence, unsettled by Phyllis's insinuations. He stops at a drive-in to drink a beer, then a bowling alley, then goes home. In voice-over narration, Walter relates his sinking feeling that he was not yet free of Phyllis's designs. He sits in the dark until the doorbell buzzes, and finds Phyllis, who has come to return his hat that he left behind. He invites her in and turns on the lamp, and Phyllis implores him not to think her evil—to "be nice" to her like he was at their first meeting. She describes how suffocating Mr. Dietrichson is, and asks Walter if he wants her to leave. He says yes, but when she moves to leave, Walter pulls her back into an embrace and they kiss.
Later, drinking bourbon together, Walter pointedly mentions two seemingly innocent deaths with accident insurance payouts in which the wives were later tried and convicted. Phyllis describes how coldly Mr. Dietrichson and Lola behave towards her, and explains that she had been the nurse who looked after Mr. Dietrichson's first wife, who died. She says that Mr. Dietrichson is a controlling and abusive husband, and although she maintains she doesn't want to kill him, she still wishes he were dead. Walter assures her that such a death, especially one involving an accident insurance policy, would be instantly obvious to claims investigators.
In voice-over narration, which flashes forward to Walter speaking into the dictation machine, he admits he had been thinking about how to defraud an insurance company long before he met Phyllis, comparing his position to a croupier who wants to figure out how to "crook the house." When Phyllis moves to leave, reiterating her hatred of living with Dietrichson, Walter tells her in a moment of passion that he will help her commit the perfect murder—perfect "straight down the line." He tells Phyllis to call him the following day from a pay phone, and she leaves. Speaking into the dictation machine in the future, Walter explains to Barton that he was trying to "think with [his] brains," in order to pull off the perfect crime.
Wanting a witness to be present when Mr. Dietrichson signs the policy, Walter and Phyllis choose Lola, which makes Walter uneasy. The four of them sit in the Dietrichson living room as Walter tries and fails to talk Mr. Dietrichson into the accident insurance policy. Lola leaves to go roller skating with a friend named Ann Matthews, although Phyllis and Mr. Dietrichson suspect that she is in fact going to see someone named Nino Zachetti. Walter deceives Mr. Dietrichson into signing both the auto renewal policy and the accident policy, saying the latter is merely a duplicate. Mr. Dietrichson retires upstairs and Phyllis sees Walter out. On the other side of the front door, Walter urgently instructs Phyllis to tell Mr. Dietrichson to take a train to Palo Alto at the end of the month, rather than drive. He tells her about "double indemnity"—a clause that stipulates a doubled payout for certain types of uncommon accidents (like falling from a train).
Getting into his car, Walter realizes that Lola is waiting inside in the passenger seat. She asks him to drive her to her destination to meet a friend. Along the way, she tells Walter how her father doesn't understand her, and Phyllis hates her. She admits that she's going to meet not Ann Matthews, but Nino Zachetti—a "hot-headed" college dropout who recently lost his job as an usher at a cinema. When Walter drops Lola off, Nino approaches the car and scolds her for telling their business to Walter. Lola says Walter's a friend, but Nino says he has no friends. They stroll away on the sidewalk as Walter's voice-over narration reveals that he felt uneasy getting to know Lola and Nino at all, given what he and Phyllis were about to do together.
Not wanting to talk on the phone or meet at the office, Walter and Phyllis choose a big market in Los Feliz as a meeting place. Walter explains that both the automotive renewal and accident insurance policies have been signed, and that he solicited a check from Mr. Dietrichson ostensibly for the automotive renewal policy that will instead be used for the accident insurance policy. As a result, he still needs Phyllis to write the original check for the automotive renewal policy. He drops the policy into her bag, and tells her to put it in Mr. Dietrichson's safety deposit box.
Phyllis then tells Walter that Mr. Dietrichon's trip to Palo Alto has been canceled, due to the fact that Mr. Dietrichson suffered a fall on a job site and broke his leg, now in a cast. Walter wants to wait and stick with the original plan, but Phyllis wants to change the plan and act immediately, afraid that Mr. Dietrichson will find out about the accident insurance policy. Walter worries that they're losing their heads; Phyllis worries that they're losing their nerve. Walter eventually persuades her into sticking with the original plan. When she tremulously explains how much she misses him, Walter reassures her that he's thinking of her "every minute."
Analysis
Although Wilder's film ultimately paints Phyllis as the "femme fatale" antagonist—a woman who has subtly influenced the commission of multiple murders—Walter exhibits key moral failures that make him vulnerable to her manipulations. Alcohol is a symbol that reflects Walter's moral weakness in the face of his sexual and romantic attraction to Phyllis: at their second meeting, he initially requests a beer, and desperately seeks one out after he leaves. When she first shows up at his apartment, the two share bourbon together. Although Walter wishes he had "pink, bubbly stuff," the dark liquor more accurately reflects the style of romance that Walter and Phyllis have cultivated: rather than share something romantic and mild together, the two are building a dangerous, intoxicating, potent bond.
Moreover, Walter admits that he has always been curious to know whether he could defraud an insurance company as an insurance salesman, indicating that Phyllis has merely fomented a preexisting quotient of criminality rather than corrupt him wholesale. In this sense, Walter is a classic film noir protagonist: an antihero who is susceptible to erotic temptation, attracted to vices like cigarettes, alcohol, and gambling, and seemingly unable to control his own behavior in any of these spheres.
Walter tells Phyllis the murder needs to be perfect "straight down the line," launching an extended metaphor about trains and railways used to characterize their relationship throughout the film. According to the logic of this metaphor, Walter and Phyllis's murder scheme makes them train passengers on a journey they must take together to a final destination, which Walter realizes too late is a cemetery—with no chance of escape, detour, or surrender. Walter continually describes the machinations of the plot in language similar to the machinery of a runaway train: "The gears had meshed. The machinery had started to move and nothing could stop it...," reflecting also the fact that Mr. Dietrichson's murder will later take place on a train from Glendale to Palo Alto.
This sequence also begins to flesh out the motif of the doppelgänger or the "double," already evident in the title of the film, which refers explicitly to a clause in an accident policy indicating a double payout. Phyllis explains that she is Mr. Dietrichson's second wife, whom we later learn Phyllis killed in order to replace her. Lola is also a kind of double for Phyllis, competing with her for Mr. Dietrichson's attention and Nino Zachetti's and Walter's affections. Nino himself is a double for Walter—another male character whom Phyllis sexually manipulates in order to accomplish her nefarious goals. Phyllis and Walter's plan entails Walter impersonating Mr. Dietrichson and becoming his double on the train to Palo Alto. The film makes constant references to doubleness, not least of which is the aforementioned train metaphor, in which Phyllis and Walter are doubles of each other, fatally strapped together as a pair.
Finally, Walter and Barton are doubles—Walter admits into the dictation machine that he was trying to "think with [Barton's] brain," in order to plan the perfect scheme. The "little man" in Barton's stomach that alerts him to insurance fraud is essentially synonymous with the kind of moral conscience Walter lacks, although Walter feels his chest pang at various points throughout the film, such as when he first leaves the Dietrichson residence, or when he drives Lola to meet Nino Zachetti. Walter expresses his love and affection for Barton multiple times, and Wilder essentially frames the entire film as an intimate memorandum from the former to the latter, whom Walter must deceive in increasingly complex ways until he finally confesses via dictaphone.
