Baldly stated, some of the fundamental functions of film music are to secure that the plot gets through and to enhance our pro-attitude towards certain characters and whatever they might wish for (see Langkjær 2000).
As the film begins, two German couriers carrying exit-visas have been killed. Major Strasser arrives from the third Reich to secure that thefamous resistance leader, Victor Laszlo, will not succeed in leaving Casablanca. This war/thriller plot is intensified with the confrontation between Strasser (with some dubious help from Renault) and Laszlo. Narrative closure is achieved as he - and his wife - leave Casablanca on an airplane and Major Strasser is shot. Thus, the thriller plot provides some limitations that puts pressures oncharacters. It gives the plot a forward drive, and leads to some final action that closes down the chain of events. Even though the romantic plot somehow complicates the thriller plot, it is the thriller plot that forces Rick to decide on love. In this (narrative) sense, the thriller plot is the central plot that frames and structures the chain of events, and the love-plot a secondary one. But as isoften the case, the secondary plot-line is the most interesting, the one the audience really cares about. And even though some musical attention is given to the central plot in the last third of the film by use of suspenseful musical motives and harmonics, the music in the first half of the film concentrates on two other functions: to characterize the place and to characterize the inner state ofthe two central persons of the romantic plot, Rick and Ilsa.
In the first quarter of Casablanca, underscoring has "characterization of locale" as its major functions. Arabic sound-alike melodic figures are heard (pentatonic scales and movement along chromatic intervals, enhanced in its cultural color by instrumentation). Whereas the film as such supplies its audience with a rich, varied, andnumerous cast of characters and a more narrowly focused suspense-plot, the music focuses on place. The only deviation is the chase scene, mentioned above, taking place in the streets of Casablanca. No music related to the psychology of the characters will be heard before Rick and Ilsa meet.
As Time Goes by is heard as the first quarter of the film has passed. In terms of plot structure this fits inwith the first so-called plot-point (Field 1979), that is, some action or event in a scene or sequence that gives the plot a new direction and supplies it with a forward drive. Everybody has been presented at Rick's Café Américain, except for two people that up until now have only been spoken about: Victor Lazslo and Ilsa Lund. An important set-up is the fact that Ugarte has been arrested forhaving stolen the much needed exit visas some few moments before they enter the cafe. And from that moment, it will be more and more clear that both Strasser and Renault will do anything in their power to prevent Laszlo from having those exit visas (which, by the way, happen to be hidden in Sam's piano) and leaving Casablanca. And, in return, Laszlo will do his best to succeed in leaving (thethriller plot). Secondly, the verbal exchanges, acting, and editing make it all to clear that there is a past between Rick and Ilsa yet to be revealed to the audience (the romantic plot).
As the two enter the café, Ilsa gives Sam a strange look and vice versa. Later, Ilsa asks a waiter to call Sam over and he places himself at the piano (for those who find bad continuity funny, the very useful pianothat suddenly appears next to the table of Ilsa is absent in previous shots). Ilsa asks questions about Rick, and Sam obviously feels this to be unpleasant. At a certain point she asks him to play some of the old songs: "Play, it Sam. Play As Time Goes by." As Sam replies "I'm a little rusty on that," Ilsa insists: "I'll hum it for you." And so she does. When he plays it on the piano, she will...