The work is scored for solo piano and large orchestra with a particularly large percussion section. It is in four movements: Molto Allegro, Scherzo (Vivace), Appassionato (Andante), and Allegro. The last two movements are linked together.
While the work is basically tonal (centered in B flat), there are many atonal sections, and, in the trio of the second movement, a section of strict twelve-tone writing. The rhythms throughout the work are highly irregular and meters change often.
The first movement (Molto Allegro), the largest in scope, uses Sonata-Allegro form in an original way. After a few bars of introduction by the brass section, the solo piano enters with an extended cadenza accompanied by percussion and harp, introducing the first theme – a savage three-note motto. This highly energetic section reaches a peak climaxed by a piano run which concludes on the orchestra’s opening note – E. A sudden pianissimo for the full orchestra introduces a change of tempo and mood. The following long, lyrical orchestral tutti introduces and expands the movement’s second theme – a cantabile melody first heard in the solo horn – and shortly builds to a large orchestral climax. A sudden change of tempo begins the development section, in which two opposed metamorphoses take place: each theme is separately developed, transforming the aggressive three-note motto into a lyrical theme, and the lyrical theme into a savage motto. In other words, each one becomes the other. The cadenza in the recapitulation leads to the second theme in its original lyrical form, followed this time by a diabolic coda which brings the movement to an end.
The second movement is a short scherzo which spells the emotional tension generated in the first movement and to be continued in the third. Three short repeated chords form the scherzo’s motto, which is based on the superimposition of major and minor thirds. This interval of a third forms the building block of the movement. The trio is based on a twelve-tone row derived from the piano figures in the beginning of the movement. This tone row, however, is not an atonal one, being strongly centered on E. The recapitulation of the original material leads to a whispered conclusion of the movement.
In the third movement (Appassionato), all the themes are based on six notes. The form is arch shaped, building to a peak and diminishing to a quiet pizzicato strings and a hushed single-note piano melody which leads directly into the final movement.
The final movement (Allegro) is a rondo. Its major theme – a fugato – utilizes orchestral and piano tone-clusters as an integral part of its structure. The three subsections of the movement incorporate the major themes from the earlier three movements. The first subsection reiterates the slow third-movement theme (now played at a fast tempo); the second subsection (a buildup of the coda) recalls the scherzo’s material; and the final section at the end of the coda brings back the original three-note motto of the first movement, joining to end the concerto in a burst of virtuosic energy and color.
– John Corigliano