Sundered Faith is a d20 System scenario for four to six 6th- to 8th-level characters. Part of AEG's Adventure Keep line of short, cheap modules in half-sized format (4-1/4"x11"), it is intended to be run as a single session. From the back cover:

FOR PUBLIC POSTING:

Last week, several laborers who were working to clean up the damage to our sewer caused by the recent earthquake have been found brutally murdered. Until further notice, citizens should stay clear of any sewer gratings, openings, or tunnels for their own safety. Do not allow children to play unattended in areas where such openings are known to exist.

The governor is assembling a group of interested persons to investigate these murders. Each member of the investigation team will receive 500 gp up front, with an additional 2,000 gp to follow upon a thorough and satisfactory completion of the investigation, provided evidence that the matter has been dealt with is presented to the governor. If you desire to join this investigation, please apply at City Hall.