How on Earth was their plan supposed to work? All they know about the white walkers and the army of the dead is that they seem to stick together, and they don't need food or sleep like a traditional army. So how were they expecting to isolate a single zombie, who don't go out on their own, and take it without alerting the ENTIRE ARMY OF THE DEAD who would be in the immediate vicinity? It's the most bone-headed plot anyone on the show has come up with, to the point that you can't believe anyone would think it would work. That piece was just about the most garbage thing the show has done.
That aside, it was a great episode.