In the Season 3 finale of "Elementary," we saw Sherlock Holmes (Jonny Lee Miller) slip back into drug-use after a period of sobriety, and this was brought about by him being forced to work with his former drug dealer, Oscar (Michael Weston), in order to rescue his ex-sponsor and friend, Alfredo (Ato Essandoh).

Alfredo was saved, with the help of Joan Watson (Lucy Liu), Detective Bell (Jon Michael Hill) and Captain Gregson (Aidan Quinn). But Joan was not able to save Holmes from relapsing into his drug addiction.

Joan started out as Holmes' sober partner in Season 1, and evolved to become his friend and consulting partner. There are questions as to whether Joan will revert to sober partner in Season 4 with this new turn of events. According to Entertainment Weekly, Executive producer Robert Doherty said that Joan's role in helping to maintain Holmes' sobriety is now over.

"Joan will not revert to sober companion mode," Doherty said. "She's past that now. Yes, she can and will be helpful to Sherlock, but primarily as a friend and a partner."

The finale raised some questions that fans expect to be answered in Season 4, the first being is Oscar still alive? In the finale, Holmes beat up Oscar pretty bad when he found out Oscar knew that Olivia, his sister, died of heroin overdose because of his own bad habits. It is not clear whether Oscar was dead or alive after Holmes' attack.

Another question is what really happened in the 3 days that were missing—Holmes entered a dark tunnel with heroin and 3 days later, was found by Joan on a rooftop, already in full drug-use mode.

Doherty told TVLine that the events in those three days will be explained in Season 4. "It's quite possible that he returned to Joan and Gregson and Bell the same day that Alfredo was rescued," Doherty said, adding that Holmes did not just go on a drug-use spree during those three days.

We will get to know what Holmes' Dad is really like. At the end of Season 3, we found out that Holmes' father is on his way to Brownstone. Doherty told Entertainment Weekly, "Sherlock's dad, like Sherlock, is a complicated man. When Sherlock has described him, he hasn't painted a picture of a very loving father ... and yet it's worth noting this will be the second time he's taken steps to help his son during a difficult time."

Doherty also teased to Entertainment Weekly that we might be seeing Moriarty (Natalie Dormer) in season 4.

"Elementary" season 4 is expected to premiere on Thursday, Nov. 5, on CBS.