Property related query

Sir I purchased a agriculture land and we taken all the position after 2 months a notice raised regarding stating that the property is made an agreement to another person,after receiving the notice we approached the lawyer which we consulted earlier to purchase the property he given a written notice to the lawyer asking any documents proof he didn't given reply time has passed for another six months again the other parties lawyer send me a court summons regarding the above ,due to nature of duty I stay most of the time out of station die to this the summons received by my wife . Before purchasing the property we made a paper add stating that any one having objections regarding the property. no one came and after registration they r harnessing but any thing he is stating he has given a token amount twenty lakhs . One more thing the person who sell the property to us having another properties and a house in his name . All the documents which we purchased is in our title I had my pass book and 1 B namuna and I am paying the land tax also in his what is he worst case of the judgement please advice