They're called caves. Rooms deep within the bowels of mortgage servicing shops across the country filled with paperwork. Tens of thousands of files in one room. According to Lender Processing Services, there are 6.9 million noncurrent loans in America as of Aug. 1. Of those, 2.6 million borrowers are beyond 90-days delinquent but not in the foreclosure process. These lost borrowers trapped somewhere in the shadow inventory of loss mitigation are out there, and a growing number of high-touch servicers are trying to reach them.