Directed by: Richard Quine
Written by: Stephen J. Cannell
Air Date: December 4, 1973
Previous: Candidate for Crime
Next: Publish or Perish
Guest Starring: Robert Culp, Louise Latham
"Double Exposure" is the fourth episode of the third season of Columbo.
Dr. Bart Keppel (Robert Culp, in the third of his four appearances on Columbo, the first three as the murderer) is an expert in the field of "motivational research", namely, how to use advertising to get people to buy things. Among other things, he is a pioneer in the use of Subliminal Advertising, the insertion of single frames of images into films in order to subconsciously influence people to buy a product. For example, inserting a single frame of a bag of popcorn into a movie will lead moviegoers to buy popcorn at the concession stand.
Keppel is showing a motivational film to one Vic Norris, a businessman and client. Norris is pretty pissed-off at Keppel, because Keppel has tried to ensnare him into blackmail via the use of a Honey Pot named Tanya Baker. Norris isn't cooperating, however, and has threatened to go to the police to report Keppel's blackmailing. So Keppel kills him, by using a combination of some extra-salty caviar and a subliminal insert to make Keppel thirsty during a film Keppel is demonstrating, and then shooting him in the chest when Norris exits the screening room to get water (with his alibi that he's providing narration to the film).
He has two problems, though. First, there's the projectionist, Roger, who saw Keppel monkeying with the hall monitor and eventually figures out that Keppel killed Norris. Secondly, there's Lt. Columbo, who notices the usual niggling details (if the killer came from the street outside, how would they know when Norris was leaving the screening room?), and begins to zero in on Keppel.
- Bullying a Dragon: Roger the projectionist figures out how Keppel committed the crime. He then demands $50,000 for his silence. Keppel kills him instead.
- Continuity Nod: Columbo mentions offhandedly that he hasn't been getting much sleep because he's been up late working on "the Hayward case". That's a reference to the previous episode, "Candidate for Crime".
- The Ghost: Tanya Baker, the Honey Pot model whom Keppel used to manipulate Norris and whom he's apparently used more than once in similar schemes. She's discussed several times, and Columbo even mentions calling her, but we never see the character.
- Hidden in Plain Sight: The gun used to shoot Norris was hanging on the wall in Keppel's office the whole time. Keppel used a caliber converter to make the gun fire a different type of bullet than what the gun was chambered for to throw the police off the trail.
- Hoist by His Own Petard: How Columbo gets Keppel in the end. He puts some subliminal inserts of his own into Keppel's film, photos showing Columbo searching Keppel's office. It works, as Keppel goes back to his office to check, and pulls out the caliber converter hidden in a lamp, at which time Columbo steps out of the shadows.
- Idiot Ball:
- Keppel just had to hold on to that caliber converter. Couldn't have, say, thrown it into a random garbage can somewhere.
- Once White figures out how Keppel committed the murder, he blackmails him for $50,000 without anything to dissuade Keppel from murdering him too. Even more stupid is he naively believes that Keppel will follow through, and gets shot at his secondary job while alone in a projection booth.
- I Know You Know I Know: Columbo and Keppel start playing this game right around the time that Keppel, with Columbo's prompting, explains how someone could have hypothetically gotten Norris to leave the theater via subliminals, especially by encouraging him to eat salty caviar before the screening to make him thirsty. They play this game some more when Columbo confronts Keppel at the golf course and starts asking uncomfortable questions about Tanya Baker. Keppel cheats at his golf game, pulling a ball out of the rough and saying very pointedly to Columbo, "and no one will ever know." After this Columbo drops the facade and, in response to a challenge from Keppel, says that he thinks Keppel killed Norris.
- No Warrant? No Problem!: Subverted. Columbo goes to Keppel's office with a police photographer. As the photographer snaps pictures while Columbo looks around, he protests about searching without a warrant. Columbo says "We're not searching, we're looking". And he's right, as what he's really doing is setting up the pictures that he will use as subliminals to get Keppel into the office.
- Phoney Call: A twist on the trope. Keppel starts out by narrating his movie for Norris and the rest of the audience. Then he starts playing a tape of his narration. He then ducks out of the darkened theater to kill Norris without anyone realizing he's gone.
- Reclining Venus: In Dr. Keppel's motivational film about advertising, there is a shot of a half-lying, half-sitting model in a bikini.
- Simultaneous Arcs: As shown in Continuity Nod above, Columbo off-handedly mentions working on the Hayward case. Given that he's talking in present-tense, it's implied that "Candidate for Crime" is happening concurrently with this episode, specifically within the prolonged time gaps in which Columbo is off-screen.
- Skeleton Key Card: How Keppel gets into the Norris home to plant a gun in an effort to frame Mrs. Norris. Probably possible in the 1970s, although one would think a home as fancy as that would have a deadbolt.
- Subliminal Advertising: The whole plot. The show ends when Columbo uses subliminal inserts of his own to subconsciously influence Keppel into going to his office and searching for something incriminating—namely, a caliber converter.
- They Call Me Mister Tibbs: Columbo repeatedly addresses Keppel as "Mr. Keppel", only for Keppel to irritatedly correct him with "Dr. Keppel." It's obviously a deliberate effort by Columbo to irritate his suspect.