Please don't confuse this with George Benson's "This Masquerade." This is from the Great American Songbook, and there are many great recordings of The Masquerade Is Over. Nancy Wilson did it as a ballad with the Cannonball Adderley Quintet, and it has been recorded by Sarah Vaughan, Carmen McRae, Etta James, Aretha Franklin, Al Jarreau, Jimmy Scott, even George Benson - and this is not a comprehensive list! Instrumentally it's known as an alto sax tour de force: Sonny Stitt, Jackie McClean, Lou Donaldson, Sonny Criss among my favorites. Tenor players Gene Ammons and Ike Quebec did it, too.
In the late '50s Blue Note released jazz 45s (in addition to 33s) and many recordings featured Ray Barretto on congas. Lou Donaldson's Masquerade Is Over was one of them - always on the play list in my buddy Bill's '54 Buick, a two door hardtop with a "rake." Before 4 track tape, and before 8 track tape, you could have a 45 player in your car. The records played upside down and as each one finished, the spindle "keepers" opened just long enough to allow the record just played to drop down on a catcher tray. Coincidentally, one could find cookie cans at Walgreens that held 45s perfectly with just the right amount of margin around the edge. Passenger in charge of programming...
Masquerade Is Over was recorded in either F or Eb by the alto players, and I would guess that vocalists were all over the map when choosing their key, so here's the chart in Roman Numerals. There's a version by Lou Donaldson out at YouTube with his solo neatly transcribed!
Full title, (I'm Afraid) The Masquerade Is Over, is an A A B A form but it's 16-16-8-16. The first 12 of the A section are the same every time but the last 4 change, so there's 1st, 2nd and 3rd endings (3rd written as a Coda). If one simplifies all the ii-Vs to just the dominant chord, breaking the song into 4 measure chunks, here's what you get for the first 12:
I-III-II-I7 IV-VI-II-V I-I7-IV-bVII.
(remember bVII can "relax" back to I.)
First ending is a iii-VI-ii-V turn-around. 2nd ending has a quick iii/VI-ii/V in measures 29-30. The minor iii in measure 13 and 29 is a "substitute for I."
Measures 31-32 rest on the tonic and a VI7 on the last two beats of bar 32 sets up the bridge that will start on ii. Note the bVII on the last two beats of bar 31 - sometimes added by convention to spice up the return to I. It could be voiced as minor iv/b7. Alternately the last two beats of 31 could be bVII-natural VII, a chromatic return to the I in bar 32.
The first 4 bars of the bridge can be simplified to V7-VI7-V7- Major I (again by ignoring the minor 7th chords preceding the dominants). Then in a surprise move the 1st chord in bar 5 of the bridge is a #iv half-diminished, a tritone away from the I. In the original key the second half of the bridge starts out #ivb5/VII - iii/VI9 - vi/II7 - ii/V to return us to the I of the A section. It can also be thought of as a sudden modulation to II Major: quick ii-Vs on VI7-V7-I7 in the new key followed by a quick ii/V in the original key.
The "Coda" (3rd ending) is similar to the 2nd ending but the I chord is more conclusive. With the 16-16-8-16 format, the very last measure becomes bar 56 - optionally a quick ii/V starting the song over for soloists or a final return to the melody. If there's a tag at the end, measures 53-54 would repeat. Ultimately, it's easier to play than describe, but sometimes it pays to zoom out and look at the overview.