Mass Effect Story Explained: the Trilogy and Andromeda

Mass Effect is BioWare's science fiction series: a trilogy released between 2007 and 2012 that follows Commander Shepard, and Mass Effect: Andromeda (2017), which starts a new story in another galaxy. The trilogy runs from 2183 to 2186 and is one long argument with the Reapers, the machines that harvest advanced life every 50,000 years. Shepard's choices carry from game to game, so a lot of what follows depends on how you played. This page covers every game in order at a high level, with full spoilers, and links to a detailed page for each. (Mass Effect; Mass Effect 3; Mass Effect: Andromeda)

Before the story begins#

Humanity found a Prothean data cache on Mars in 2148 and, with it, the technology to travel between stars using element zero and the mass relays. Within a decade humans had fought the turians in the First Contact War and joined galactic society on the Citadel, the station where the Citadel Council governs. By 2183 the Systems Alliance wants a seat on that Council, and the older races don't trust it. The Protheans, who seemed to have built the relays, vanished 50,000 years earlier and nobody knows why. For the full dated history, see the Mass Effect timeline. (Mass Effect)

Mass Effect (2183)#

Shepard is executive officer of the Normandy SR-1 under Captain David Anderson when geth attack the colony of Eden Prime. There the turian Spectre Saren Arterius murders his colleague Nihlus, and a Prothean beacon burns a confused vision of slaughter into Shepard's head. (Mass Effect)

Once Shepard proves Saren betrayed the Council, Shepard becomes the first human Spectre and hunts him across the galaxy with a crew that includes Garrus Vakarian, Tali'Zorah, Urdnot Wrex and Liara T'Soni. On Feros, Noveria and Virmire the picture comes together. Saren's flagship, Sovereign, is a living Reaper, and Saren is under its influence. The Reapers destroyed the Protheans and every advanced civilisation before them. On Virmire Shepard has to leave either Kaidan Alenko or Ashley Williams behind to die. (Mass Effect)

On Ilos a Prothean VI called Vigil explains the trap. The Citadel is a giant mass relay to dark space, and Sovereign plans to open it so the Reaper fleet can return. Saren reaches the Citadel first through the Conduit, a hidden Prothean relay. In the Battle of the Citadel, Saren dies and Sovereign is destroyed. Shepard decides whether to save the Council at the cost of human lives, and humanity gets a Council seat either way. The Reapers are still out there. Full detail is on the Mass Effect story page. (Mass Effect)

Mass Effect 2 (2185)#

Weeks after the Battle of the Citadel, an unknown ship destroys the Normandy and Shepard dies in orbit. The pro-human group Cerberus, led by the Illusive Man, spends two years and billions of credits bringing Shepard back. The reason soon becomes clear. Whole human colonies are vanishing, and the Collectors, a mysterious race from beyond the Omega 4 Relay, are taking them. (Mass Effect 2)

Shepard can't count on the Council, which has decided Sovereign was a geth ship, so the game is about building a team for what everyone calls a suicide mission. Miranda Lawson and Jacob Taylor come from Cerberus. Mordin Solus, Jack, Grunt, Thane Krios, Samara and, if Shepard reactivates it, the geth Legion join the returning Garrus and Tali, and each recruit has personal business Shepard can help settle. The crew learns the Collectors are what is left of the Protheans, rebuilt by the Reapers as servants. (Mass Effect 2)

Through the Omega 4 Relay, Shepard's team storms the Collector base and finds what the abducted humans were for: a human Reaper being built from their liquefied bodies. Shepard decides whether to destroy the base or hand it to Cerberus, then destroys the human Reaper. How many of the team survive depends on how well Shepard prepared, and if things go badly enough Shepard can die too. In the Arrival add-on, Shepard destroys the Alpha Relay to delay the Reaper fleet, killing hundreds of thousands of batarians. Full detail is on the Mass Effect 2 story page. (Mass Effect 2; Mass Effect 2: Arrival)

Mass Effect 3 (2186)#

The Reapers arrive. They take batarian space, then hit Earth while Shepard is grounded awaiting trial for the Alpha Relay. Shepard escapes, and Anderson stays to lead the resistance. In the Prothean archive on Mars, Liara finds plans for the Crucible, a device that every cycle has added to and nobody has finished. (Mass Effect 3)

The rest of the war is coalition building. Shepard brokers deals with the turians, krogan and salarians, which means deciding whether to cure the genophage on Tuchanka. Over Rannoch the quarian and geth war comes to a head, and the outcome ranges from peace to the extinction of one side, depending on earlier choices. Cerberus, now indoctrinated, fights Shepard at every step. Its assassin Kai Leng takes the Prothean data from Thessia, which reveals the Crucible's missing piece, the Catalyst, is the Citadel itself. The Reapers have moved the station to Earth. (Mass Effect 3)

In London the combined fleets attack and Shepard reaches the Citadel. Anderson and the Illusive Man both die there. Shepard then meets the Catalyst, an intelligence that created the Reapers to stop synthetic life wiping out organic life. It offers Shepard a choice: destroy every synthetic, Reapers included; control the Reapers; or merge organic and synthetic life in Synthesis. The free Extended Cut adds a fourth option, refusing, and fuller epilogues. Every ending is explained on the Mass Effect 3 ending page. (Mass Effect 3; Mass Effect 3: Extended Cut; Mass Effect 3: Leviathan)

Mass Effect: Andromeda (2819)#

Andromeda leaves the trilogy behind. In 2185, while Shepard was fighting the Collectors, the Andromeda Initiative sent the Nexus station and four arks of sleeping colonists to the Andromeda galaxy, a trip of more than 600 years. None of the colonists know what happened with the Reapers. (Mass Effect: Andromeda)

The human ark Hyperion reaches the Heleus Cluster in 2819 and finds nothing as promised. Its "golden world" is barren, an energy phenomenon called the Scourge cripples the ships, and the Nexus is short of food after an uprising. The human Pathfinder, Alec Ryder, dies on the first planet and the title passes to one of his twins, Scott or Sara, along with the AI SAM. (Mass Effect: Andromeda)

Ryder learns that ancient Remnant vaults can make whole planets habitable, and that a hostile species, the kett, wants them too. The kett have been at war with the native angara for decades and turn captured angara into more kett. Ryder settles Eos and other worlds, wins over the angara and finds the hidden world of Meridian, which controls every vault in the cluster. There Ryder defeats the kett Archon and secures a home for the Initiative. Full detail is on the Andromeda story page. (Mass Effect: Andromeda)

In what order#

Play them in release order: Mass Effect, Mass Effect 2, Mass Effect 3, then Andromeda. The trilogy is a single story with save imports, so the second and third games remember what Shepard did. The Legendary Edition (2021) bundles all three with most of their add-ons. Andromeda can be played on its own and doesn't need any trilogy knowledge beyond the basics of the species. (Mass Effect Legendary Edition; Mass Effect: Andromeda)

• Mass Effect (2183): Saren, Sovereign and the Battle of the Citadel. Story explained.
• Mass Effect 2 (2185): the Collectors and the suicide mission. Story explained.
• Mass Effect 3 (2186): the Reaper War and the endings. Ending explained.
• Mass Effect: Andromeda (2819): the Initiative in the Heleus Cluster. Story explained.

Where the story stands#

The trilogy ends in 2186 with the Reaper War over in whichever way Shepard chose, and the series has never said which ending is canon. Andromeda ends in 2819 with the Initiative settled in Heleus, the kett Archon dead and the quarian ark still missing. The wider history of both galaxies is on the Reaper War and Andromeda Initiative pages. (Mass Effect 3; Mass Effect: Andromeda)