"The Flash" and "Arrow" may be on a Thanksgiving break but they promise to return with an explosive crossover two-part episode. After a teaser image was posted last week, fans of the superhero shows now get an official trailer that gives a glimpse of what to expect.

The CW has posted the official crossover trailer for the episodes coming on Dec. 1 and 2 for "The Flash' and "Arrow," respectively. As show executive Marc Guggenheim said in a previous report, it's the first "proper" crossover for the two shows in that the events from "The Flash" truly spills over to the events in "Arrow" the next day. And the brand-new trailer proves that, highlighting equally on the two shows that it feels like a trailer for just one television series. One will be unable to tell which scenes appear in which show. 

It opens with a celebration that's surely not going to last. Oliver Queen (Stephen Amell) is flanked with his romantic interest Felicity Smoak (Emily Bett Rickards) as he toasts the Star Labs Team. He tells them he's happy to see everyone again but that he wishes it's not because they are amongst some dark times.

After a brief intro from Malcolm (John Barrowman) and Carter Hall aka Hawkman (Falk Hentschel) as to the supervillain they're about to face – Vandal Savage (Casper Crump) – the action begins in the video. Click play below to see just how action-packed and intense the episode is going to be.

Also in the crossover episodes is Ciara Renée, who had been guest starring in "The Flash" for the past few episodes as the new girl Kara Saunders, a potential love interest for Cisco Ramon (Carlos Valdes). Of course, those who have been following news on "Legends of Tomorrow" will know that the romance can't last as she already has the Hawkman. And Kara is going to be Hawkgirl soon, as Cisco has "vibed" in the last episode. 

The crossover episode that's set to introduce more of the "Legends of Tomorrow" characters will air in a little less than two weeks. Part one happens in "The Flash" on Dec. 1 and continues in "Arrow" on Dec. 2.