"Arrow" season 5 episode 8 will feature an alternate timeline, where Laurel and Oliver are engaged and are living a seemingly perfect life together.

Titled "Invasion!," episode 8 will be part of The CW's biggest "Heroes vs. Aliens'" crossover.

"Oliver wakes up to a life where he never got on The Queen's Gambit. Robert and Moira Queen are alive and well. Laurel is his loving fiancée and their wedding is imminent. Everything seems perfect, but Oliver starts to notice small imperfections that make him question this new reality. Meanwhile, Felicity and the recruits take on a new threat with help from The Flash and Supergirl," reads the synopsis for the episode.

The episode will also feature an alternate reality where Oliver was never the Green Arrow.

In an interview with TV Line, actor Stephen Amell, who plays Oliver, teased that the storyline of the upcoming episode will be quite different from the previous episodes.

"It is such a radical departure from anything that we have ever done on the show. We utilize the fantastical elements that we bring in on 'The Flash' and carry through to 'Legends of Tomorrow' with the present-day storyline to create something that is not a flashback or a flash-forward. It's something else entirely," he said.

He also revealed that his character will see a therapeutic moment towards the end of episode 8, where he will be able to say goodbye to the people he never had the chance to say goodbye to.

"Arrow" season 5, episode 8 airs on November 30 on The CW. Watch the promo below.