Invisible ink

 Once there was thief - he started working for bad person - deals with them to stool a bag - that bag filled with important documents, skeches and order - bag belongs RAW agency - agency needs that document from delhi to pune - 2 officer of CBI ready to go pune from Delhi - they offer to travel by train - thief get to know about both of them - after traveling half distence - thief came into train - at night he robbed that bag - he deposit that bag to enemy - they get to know that it's wrong document - pages were blanked - Raw officer get to know of getting thief - thier reaction were normal - they brought 2 copy of documents and 2 bag to - written by invisible ink - enemy were confused and angry - documents went on right place - after that they reveal about invisible ink - conflict was they don't know about the documents for what they were used.