The Song is in the key of E and begins (on "If you wear red tonight...") with a I-IV-ii7-V7 chord
progression (E-A-F#m7-B7) in which the word "tonight" (B melody note) appears as a "delicately haunting" 4th above the F#m7.[3] The melodic pitches of this first two bar phrase are repeated (with initial repetition of the G# melody note) on "remember what I said tonight," except that the B melody note on the second "tonight" is now backed by a ♭VII (D) chord that shapes the B melody note into a more "luscious" 6th.[4] The chorus ("Yes it is, it's true. Yes it is, it's true") involves a I (E chord)- III (G# chord)- IV (A chord)- I (E chord) progression in which the major III (G#) chord appears for the first time in the Song to propel the Plagal drop from IV (A) to the tonic I (E) chord.[5]