The biggest mystery going into the end of Arrow's fifth season has nothing to do with Prometheus or Vigilante. Instead, the question on every fan's mind is, "WTF is happening with Manu Bennett right now?!"

On Monday, Arrow star Stephen Amell tweeted a photo of the mask Bennett wore as Deathstroke during his tenure as the show's early big bad. "Desperate times call for desperate measures. Welcome back @manubennett," Amell wrote.

Fans immediately were thrown into an excited tizzy, thrilled their favorite villain was returning. Bennett, however, was just plain confused. "WTF????" he tweeted in reply.

That same day, executive producer Marc Guggenheim also tweeted that "the return of @manubennett is only the first of a few exciting announcements about Arrow's [fifth] season finale," before sharing a photo of, assumedly, Bennett back in his Deathstroke costume.

Bennett, who is apparently not the person in the Deathstroke costume that's been spotted on the set of Arrow's finale, claimed Monday that, "For the record - I'm not going back for Arrow! #assumptionisthemotherofall."

As fans scratched their heads wondering why Arrow's star and executive producer would both falsely claim Bennett is returning, the actor once again took to Twitter on Tuesday to reveal it is physically impossible for him to be playing Deathstroke in the finale because he's actually in New Zealand filming MTV's The Shannara Chronicles.

However, sources confirm to that Bennett is in fact returning to Arrow for the finale and will begin shooting scenes in Vancouver later this week. (It's likely that the man spotted in the Deathstroke costume on set is filming fight scenes or other footage where it wouldn't be necessary to have Bennett film it himself.)

So what is happening here? Let's run down a few options:

1. Bennett's agent forgot to tell him that he was returning to Arrow and so he got super confused by Amell and Guggenheim's tweets.

2. Bennett was told that he would be returning to Arrow but got a very rare form of selective amnesia and forgot.

3. Bennett is a PR genius and orchestrated this situation to drum up a lot of publicity surrounding his return.

4. We're in the Matrix.

Arrow returns Wednesday, April 26 at 8/7c on the CW.

(Full disclosure: is owned by CBS, one of the CW's parent companies.)