Walt went full Heisenberg with his call to the DEA. He drew all the attention up to New Hampshire so he could (presumably steal a car and) get back to ABQ as fast as possible. The flash-forward in the second half of the season ("Hi Carol") comes before the flash-forward in the first half (at the Denny's, out of money).
So.. he goes all the way back home to pick up the ricin cigarette. Drives all the way back to NH non-stop, stops at Denny's to meet with the arms dealer, and then makes his final return "home" to confront the Aryan Brotherhood.
At this point, Walt still thinks Jesse is dead. I predict that he will show up and accidentally kill Jesse.. or that the Brotherhood will shoot Jesse right in front of Walt's face. And then Walt becomes meth-slave to the Aryans, and meanwhile, Skyler is found guilty as an accomplice and goes to jail, while Flynn, Marie, and Holly try to make the best of this awful situation.
"Executive Producer: Vince Gilligan"
Something like that.