In the year 2183, Commander Shepard is sent to the human colony of Eden Prime to recover a Prothean beacon. The mission is disrupted by an attack from the synthetic Geth, led by Saren Arterius, a rogue Spectre agent. After making contact with the beacon and receiving a cryptic vision of destruction, Shepard is appointed the first human Spectre and tasked with hunting Saren across the galaxy. The investigation leads Shepard and a growing crew aboard the SSV Normandy through multiple worlds, uncovering a conspiracy tied to the Reapers, a highly advanced machine race believed to eradicate all organic civilizations on a 50,000-year cycle. Shepard must stop Saren before he can trigger their return.