The Flash will reach out for Green Arrow's help in the two-hour special crossover episode of Arrow season 5.Facebook/Arrow

In Arrow season 5 episode 8, titled Invasion, Oliver Queen could be brainwashed and vaporised by a technologically advanced alien race called Dominators. The two-hour special episode, which marks the 100th chapter of the superhero drama, will be aired this Wednesday, November 30, at 8 pm EST on The CW.

The epic superhero crossover concluded its last episode by featuring all the earth's heroes, expect Barry Allen a.k.a The Flash, being abducted by the aliens. So it is up to Grant Gustin's character to save the heroes and the people of Star City as well as the rest of the world.

The official synopsis for the new episode hints at troubled moments for Stephen Amell's character. It states that he will wake up to a life where he never got on The Queen's Gambit. He will meet his parents Robert and Moira, wherein they are planning his wedding with his loving fiancée Laurel Lance.

The mayor of Star City enjoys his new life until he starts to notice small imperfections that make him question this new reality. Did the Dominators vapourise and brainwash him while he was in their custody? Will Barry reach out to his help before it's too late?

Click here to watch Arrow season 5 episode 8, titled Invasion live online. The special crossover episode will also be available online here.

Meanwhile, the upcoming episode of The CW series will also show Felicity Smoak and the new recruits of Team Arrow seeking the help of Supergirl and The Flash when a new threat hits Star City. Is it because they are not able to contact Oliver Queen?

Check out the official synopsis for Arrow season 5 episode 9, titled What We Leave Behind, below:

After Prometheus attacks Curtis, Oliver realises Prometheus knows all of Team Arrow's secret identities and is planning to come for them one by one. Felicity and Detective Malone discover a clue that links Prometheus to Oliver's past.