Locus is put online in issues of 24 pages each. Each issue takes two months to go fully online. Storylines will span multiple issues. This page should help you keep track of all this.
The first storyline spanned issues one through three, and told the story of Locus and Spook getting revenge for Isaac's murder. Links below will take you to the cover for that issue; you can read from there.
Issue One: El Loco Lobo
Issue Two: The Necromancer
Issue Three: No Other Choice
The second storyline turns the clock back about 20 years or so, and tells the story of Locus' father, Templeton Isaac Goodman:
Issue Four: Unveiled, Part One
Issue Five: Unveiled, Part Two