undercover

undercover (http://definr.com/undercover)

     adj : conducted with or marked by hidden aims or methods;
           "clandestine intelligence operations";
           "cloak-and-dagger activities behind enemy lines";
           "hole-and-corner intrigue"; "secret missions"; "a
           secret agent"; "secret sales of arms"; "surreptitious
           mobilization of troops"; "an undercover investigation";
           "underground resistance" [syn: clandestine, cloak-and-dagger,
            hole-and-corner(a), hugger-mugger, hush-hush, {on
           the quiet(p)}, secret, surreptitious, underground]