This engrossing Spanish-Argie thriller stars the appealingly mordant Darío Grandinetti (Probably best known from Almodóvar's Hable con Ella, but most fondly recalled by me in Eliseo Subiela's excellent El Lado Oscuro del Corazón, 1 and 2.)
Here he plays Ramón, a university lecturer who early on we see explaining on video just how he got into the business of serial-killing.
The rest of the movie basically alternates between situations in which Ramón is in the midst of an intense interview. In the first he is tormenting his ex-wife Laura, apparently his helpless captive in a well kitted-out pyscho's underground lair, whilst in the second of these cat and mouse games, two detectives are subsequently interrogating him as the prime suspect following her mysterious disappearance.
The interplay of these counterposed dramas is very well-handled. The overall mood is playful, with a bit of a nasty edge. To some extent it's also quite predictable: Ramón must create doubt in the minds of the police, and in doing so toys with our own doubts about the reality of what we see in the other section of the narrative. But this in no way detracted from my enjoyment of the way the story unfolds.
I especially enjoyed the section where Ramón gives the cops a plausible account of how he went about kidnapping his ex, which forms a voiceover overlaying a flashback which depicts the subtly different actual circumstances of the abduction.
One odd aspect of the film is the game which gives it its name. Ramón challenges Laura to respond to each word he pronounces with another beginning with the last syllable of his own. In this section the subtitles are of course unable to directly translate the Spanish words delivered by the actors as this would make little sense, but it does seem rather odd if you are listening to the spoken words whilst following the text on the screen.