Complex sentence: Unfortunately for Fromm, this reaction helped to expose his own lack of action and alleged failure to report the plot, leading to Fromm's arrest, conviction and sentencing to death by the German "People's Court" ("Volksgerichtshof").
Split into simpler sentences: Unfortunately for Fromm, this reaction helped to expose his own lack of action and alleged failure to report the plot. He was arrested, convicted, and sentenced to death by the German "People's Court" ("Volksgerichtshof").