Warning: Wikipedia contains spoilers.
The story primarily concerns the difficult relationship between two women, Francine Peters and Katina Choovanski (Katchoo), and their friend David Qin. Francine considers Katchoo her best friend; Katchoo is in love with Francine. David is in love with Katchoo, a relationship which Katchoo herself is deeply confused about. This powerfully and sensitively portrayed relationship plays itself out over a background created by the second main plot element, a thriller-style story concerning the shadowy Big Six organisation, and a woman named Darcy Parker, who uses highly trained women to infiltrate and to an extent control the political system. The two elements are slightly incongruous, and the thriller element sometimes threatens to become slightly absurd, but in general the interplay between the two generates a considerable degree of dramatic tension.
The series is famous within the world of comics for its appeal to two unusual audiences, women and people who would not consider themselves readers of comics. It is believed that the series' audience is approximately 50% female, an extremely unusual figure in the heavily male-dominated comics world.
SiP, as it is commonly known, had its genesis as a three-issue mini-series in 19??. This is now known as 'Volume 1'. Thirteen issues were published under Moore's own "Abstract Studio" imprint, and these make up 'Volume 2'. The series moved to Homage / Image Comics for the start of 'Volume 3', but after eight issues moved back to Abstract Studio, where it remains. 'Volume 3' is still ongoing.
It has been collected into a series of trade paperback collections and a different series of hardback collections. The trade paperback collections to date are: