'Arrow' season 4 episode 18 spoilers: Who dies before the clock strikes 12 in 'Eleven Fifty Nine'?; where to watch online

Team Arrow rushes to stop Malcolm, Darhk and Andy in "Arrow" season 4 episode 18.YouTube/The CW Television Network

The guessing game is on for the identity of the mystery character set to meet his or her demise in "Arrow" season 4, episode 18, titled "Eleven Fifty Nine." The title of the installment is a reference to the time of death of this certain character.

While it is unclear if the individual in question will also be the one in the grave that Oliver and Barry visit in the flash-forwards, what's set in stone is that someone is going to die in this "Arrow" episode.

Who that person will be largely depends on the events in "Arrow" season 4, episode 18. Here, Merlyn will attempt to break Darhk out of prison, a plan Team Arrow briefly learns, resulting in an action-packed standoff.

Thea takes on her father, who warns her that she can "never" beat him, while Oliver tracks down Diggle's brother Andy, who was revealed to be Darhk's "ace in the hole" in episode 17. Oliver seems to have figured that out in episode 18.

As Oliver confronts Andy, Diggle walks in on the two. The latter tells his brother that Oliver accuses him of being a traitor, as if asking for help. Diggle draws his gun and appears to point it at Oliver.

"Arrow" season 4, episode 18 will also connect the present time to the flashbacks involving the idol Baron Reiter was obsessed with. It happens to be the same object that will be used by Malcolm to set Darhk free and to give his power back.

Just as everyone thinks little Diggle is the traitor, Andy takes an arrow for Oliver in a comic-style preview of the upcoming "Arrow" season 4 episode.

Diggle comes to his brother's aid but Andy advises him to rush to Iron Heights and stop Malcolm from creating a chaos through that powerful idol.

Rumor has it that it will be Andy who dies in "Arrow" season 4, episode 18. Whether or not his name will be in the tombstone remains to be seen.

A leaked photo, however, seem to indicate that the mother of Oliver's son could be the ones in that grave. Another leak, which is largely being debunked by fans, hints it is Laurel who bites the dust. Interestingly, the voice that says "11:59" sounds to be that of the ADA's.

"Arrow" season 4, episode 18 "Eleven Fifty Nine" airs April 6 at 9 p.m. ET on CW. Watch online via CWTV.