-Remeber this guy from Season 3?:
He helped Walt and Jesse crush the trailerlab. Heeee's baaaack~
-NinjaWalt:
Seems he's out to steal something. Hopefully he remebers to roll the barrels this time. That, or...
-...Evidence from Gus' leftovers:
Me and Sticks theorized last season that the superlab security recording laptop in his office might come into play, and this may be it.
-Walt in some kind of disguise, seen opening the trunk of a vehicle:
At first I thought this may not actually be a disguise, but a flashback, but check this out...
-He's doing a drug deal:
The police already have had the face of Heisenberg described to them, so this new look may be to throw them off-course.
-Hank (walking?) in the burnt-down superlab:
He's all over the case, and as Vince Gilligan said, he knows it doesn't end at Gus Fring.
