The Ghost Sonata relates the adventures of a young student, who idealizes the lives of the inhabitants of a stylish apartment building in Stockholm. He makes the acquaintance of the mysterious Jacob Hummel, who helps him to find his way into the apartment, only to find that it is a nest of betrayal and sickness. The world, the student learns, is hell and human beings must suffer to achieve salvation. The play centers on a family of strangers who meet for the sake of meeting. They exchange no dialogue, nor gestures, they simply sit and bask in their own misfortune.

Utanför ett vackert hus sitter gubben Hummel i rullstol och smider planer mot husets förnäma invånare. En ung student passerar och dras in i gubbens hämnd.