So, we need to be geniuses? Hmmm...Let me pitch a plot:
The group was hired by Nalas Rilard, owner of Rilard Essences, a firm specializing in high-end oils and extracts for flavors and fragrances. The firm was facing a high theft rate from a workshop in Sharn that pressed exotic nuts and seeds into oils. The firm had already hired House Deneith to try and establish security, but the House had failed to identify the culprits or put a stop to the theft.
Rilard hired the unknown inquisitive firm not so much in the hopes that they would solve the problem, but to prod Deneith to pay some attention (both firms were simultaneously contracted). But the PCs noticed that the number of empty bottles for oil was not dropping as quickly as the bottles were being filled. Clearly, some of these were being emptied and returned to the rack, meaning that the processed oil was leaving the workshop but the bottles in which it had been placed were not.
While Deneith continued its unimaginative pat-down of exiting employees and careful patrols around the exits, the PCs discovered a small, unused drainage pipe that had been built into the masonry. Investigation found the other end in a disused storage area of the tower, several floors below. A ring of employees made it their business to pour quantities of the oils down the pipe during the day, always in small quantities so that their activities would not be noticed. An outside conspirator collected the liquid in clay jars. The PCs staked out both ends of the pipe, made notes of everyone involved, and presented a detailed report to Rilard (who passed it on to the Watch).
The case gained attention in part because Rilard praised the PCs' brilliance to the press as a "screw you" to Deneith, who he felt had taken his money but made only a half-assed effort. Needless to say, the affair has endeared the PCs to the mellow, sportsmanlike souls who run Deneith's operations in Sharn.
Sound OK?