Two Days Without is an epic speculative fiction collection written by Hemluin Tars.
The collection - sixteen volumes, although released simultaneously and often considered a single tome by fans - is based on the conceit of the mass relay network spontaneously shutting down for two days, five hours and four minutes. Each volume explores the consequences of this event in a particular geographical location - the Citadel, Invictus, Omega, etc. - as the unexplained loss of rapid and long-reach interstellar travel caused a spiral of events that cascade out of control.
Volume 12, "On the Loss of 'Vas'", focusing on the quarian Flotilla, is often cited as the best-written and best-researched of the sixteen volumes.