This memorandum from the Chief of the Western Hemisphere Division at the CIA reports on a major security breach related to Operation PBSUCCESS, the CIA's covert operation to depose the Guatemalan government. Messages containing cryptonyms and details of the operation were left behind in an apartment and obtained by unauthorized individuals, compromising security. The memorandum analyzes the potential impacts and exposures caused by the security breach. It also calls for further interrogation of the agent involved to investigate the incident.