It seems to me that one might summarize Pale Fire, the poem, as follows:
Canto 1: Shade's early life,
Canto 2: eschatological commitment, Maud's stroke & commitment, Hazel's story
Canto 3: Shade's grief and attempts to heal and find meaning to, or in, life. (IPH, and the White Fountain)
Canto 4: Proclamation of great insight,
description of two methods of composition, one of which is compulsive,
travails of shaving,
epilogue or envoy.