How To get hidenfield or datakey of webgrid from popup

hello Experts,

         I want to get return value from popup in asp.net MVC.

Example-

        I show the webgrid in popup .In that web grid i show the names and the datakey is Id for that names.I don't show the datakey field in my webgrid which is Hidden and then i want to get return value from popup in asp.net MVC4 which is datatkey of webgrid showing in popup. So please give the sample code or article link ..   

                                                                                                                                                                                                                  Regard's.

                                                                                                                                                                                                          (Vaibhav Hadadare)