Where did the ricin go in Season 4?
At the end of Breaking Bad Season 4, we learn that
Gus had never poisoned Brock at all. It was Walt's doing using lily of the valley; a way of manipulating Jesse into helping him murder Gus.
But if this was the case, where did the ricin go? Walt had already convinced Jesse that he could not have taken the ricin as Jesse had it with him in the morning and the only people who had any sort of access to it afterwards were Jesse himself and possibly Tyrus.
But Walt's plan hinged upon Jesse believing that Gus had stolen the ricin and used it on Brock. So Jesse couldn't have just lost it.
How could Walt have stolen the ricin? The most likely explanation IMO is that Walt stole the ricin during the three day period before the symptoms are supposed to kick in. That way Jesse wouldn't suspect him for lifting the ricin (as he would only look for any opportunities Walt may have had before three days prior to Brock's sickness). But I can't think of any opportunity that Walt had.
So, how could Walt have stolen the ricin?
Best Answer
You are correct in that Brock was indeed not poisoned by ricin but by Lily of the Valley.
But how did Walt get the ricin from him?
Huell of course! /-.-\
When Jesse is summoned to Saul's in S04E12: End Times, you see Huell pat him down for 'weapons'. However, Huell has a dirty dirty secret. He is actually a really good pickpocket!
In S05E01: Live Free or Die Saul returns the cigarette to Walt, complaining about the diabolical act he made Saul a part of (how dangerous the ricin is in addition to poisoning a child).
Walt then takes the cigarette to Jesse's house to help him get a peace of mind about it all and plants it in Jesse's Roomba to convince him that everything is a-ok in S05E02: Madrigal.
It isn't as prevalent during that episode but as I demonstrated in my answer to Jesse's realization (Answer & question has spoilers about second half of season 5) Huell demonstrates more clearly how good at pick-pocketing he is by snatching a bag of weed out of Jesse's pocket without him knowing until he reaches for it much much later.
Later on when Jesse is making his grand exit using Ed the Disappearing Man, he notices his weed is gone and puts 2 and 2 together to realize that Walt had Huell lift the ricin cigarette from him in the same manner that Saul had Huell lift the weed and figures out that Walt did indeed poison Brock in some manner, sending him down a spiraling rage that leads to the events of Rabid Dog and Ozymandias.
Pictures about "Where did the ricin go in Season 4?"
Breaking Bad Finale Theory - A Case For Walt Poisoning Brock
Sources: Stack Exchange - This article follows the attribution requirements of Stack Exchange and is licensed under CC BY-SA 3.0.
Images: Plato Terentev, Mikhail Nilov, invisiblepower, Zen Chung