Director Maite Alberti's unorthodox documentary "The Mole Agent" traces the story of Sergio, a Chilean widower, who responds to an unusual classified ad from a private investigation service. Especially strange is that the position offered is for men between the ages of 80 and 90. It soon emerges that Sergio is being hired to infiltrate a nursing home where a client has become concerned about the treatment a relative is receiving from the staff.