Complex sentence: Kim, not sharing the conspiracy's ideology and herself a former secret agent, secretly alerted her former boss Heideger, who was nevertheless unable to prevent the assassination of President Sheridan.
Split into simpler sentences: Kim, not sharing the conspiracy's ideology, and herself a former secret agent, secretly alerted her former boss Heideger. Despite having this information, however, Heideger was unable to prevent the assassination of President Sheridan.