because together, we thrive. ♪ >>> 38 miles southeast of belgrade, serbia, is the town of pozarevac.n the middle of this rural farming community is another serbian prison. out of the nation's 28 penal institutions the zabela correctional facility houses the greatest number of high-security inmates. some 1,500 in all. it would also prove to be one of the most unique prisons ever profiled on "lockup." >> translator: we have inmates who have committed some of the worst crimes and have received the longest and most severe punishments. these include inmates who are perceived to be dangerous by other facilities, a threat to inmates and security personnel alike. >> zabela, was built for 800 inmates but now houses more than 1300. the inmates considered the most dangerous of all are housed in this unit. it is called seventh block. >> translator: there are other housing units here. they call this building a prison within a prison. >> vladimir pejdo is serving four years for theft. he says he's housed here because of conflicts with other inmates. >> translator: well, i had some problems when i