From Halopedia, the Halo wiki
Episode 1: The Unknown Helper (Adjutant Reflex • Adjutant Reflex posts • Forerunner email • Halo 3: The Cradle of Life • Transmission Log) Episode 2: Flood Control (Flood Containment Control) Episode 3: Echoes Through Time Episode 4: The Great Connection (The Castaway Theory • Amazon) Episode 5: The Artifact (TheArtifactLocation.com)