简介：BuenosAires.Argentina.Thesubwaysystemhasbeenexpandedoverandover.Itisthatcomplexnowthatnobodyisabletopictureitanymore.Somedayawholetraindisappears.Fromtimetotimeitcanbeheardrushingthroughthedarklabyrinth,butitcannotbeseen.Thedirectorofthesubwaymustcomeupwithanexplanationforthisphenomenonandsendsfortheresponsibleengineer.Theengineerdoesnotwanttoseethedirectorandsendsafriend,amathematician,forinvestigation.Soontheyoungmancomesupwiththeonlypossiblethesiswhatmayhavehappenedtothetrain.Anywaythethesisissoincrediblethatnobodycanbelieveit.…