I hope this is not for real. You are joking right?
Firstly, This presumes that there is another star closer than the established closest star to our solar system, Proxima Centauri( 4.22 light years away) which is itself a memeber of a Alpha Centauri triple star system. So, from the best of modern astronomy, we do not have a close neighbor star(we'll call it "nemesis"), with which we are interacting.
Secondly, if there were a planent in binary orbit(presumably orbiting both stars) around us and nemesis, then it would be impossible to find it until it did make a very close passby of Sol. You see, if this planet is not emitting any light(non star's do not emit visible light - I know some joker will say something about jupiter), then the only light we would be able to see is that reflected from our star or reflected from nemesis. Since we can't find friggen nemesis itself, there is no hope of finding the planet until it came VERY close to Sol itself. If something like this actually did happen, it would be concidered a rogue interstellar planet anyway BECAUSE THERE IS NO NEMESIS!!!!!
Finally, don't you think a story like this would have gotten a little airtime by now?