Jacob Taylor is on vacation aboard a cruise ship when it is suddenly boarded by batarians, a four-eyed humanoid species who are often hostile to humanity. Jacob fights off the batarian pirates and travels to the Citadel to meet his former commanding officer, Major Derek Izunami. Taylor's trip coincides with the arrival of an ambassador from the Batarian Hegemony, Jath'Amon, who is due to meet the Citadel Council for peace talks. Izunami asks Jacob to investigate the batarians in the Terminus Systems. When Jacob arrives at the Nemean Abyss to meet an informant named
Miranda Lawson, he is forced to deal with human pirates who have taken over a local space station. Once he has dealt with the pirate leader "Black Eye" Clint Darragh, Miranda offers to cooperate with Jacob and gives him three leads to investigate: a
turian arms smuggler named Illo Nazario who is hiding on Tortuga; the raising of a batarian army on the planet Bekke, which is a departure from their conventional tactics of forming small terrorist cells; and reports of human doctors and scientists being kidnapped by the batarians and being taken to the Ahn'Kedar Orbital Platform. Jacob discovers a large stash of Element Zero on Bekke, rescues the
asari scientist Batha with the help of a
krogan mercenary named Nax at Ahn'Kedar, and infiltrates Illo's base using a passcode given by Ish, a
salarian contact of Miranda's. After confronting Illo and learning of his illness, Jacob deduce that the batarians are working on a biologically engineered disease and Illo was used by the batarians as a test subject. Batha synthesizes a vaccine which could neutralize the biological weapon; after being cured of the disease, Illo reveals that the batarians intend to unleash it on the Citadel Council through Jath'Amon, who has the vaccine. Jacob and Miranda hurry to the Citadel where they foil the batarian plot and save the Council. Jath'Amon swears vengeance against Jacob and the human race and is escorted out by Citadel Security. Jacob goes on another vacation and is surprised when Miranda brings a bottle of champagne along to join him. ==Reception==