Last night's all-new 'Arrow' installment, "State V. Queen," introduced some shocking twists and returned a few familiar faces along the way, but will the CW-DC drama keep the same momentum on December 4 when Grant Gustin's Barry Allen flashes into town? See the future scarlet speedster in the first trailer for 'Flash' spinoff setup "The Scientist" right now!

Though we'll have to wait an additional week before our future 'Justice League'-r makes his 'Arrow' debut, The CW has released a longer trailer for December 4 episode "The Scientist," in which Central City police scientist Barry Allen comes to Oliver's aid in a case that has mysterious ties to the detective's past. In the meantime, it seems as if Oliver's secret identity will come under fire once again, which may necessitate the hooded hero changing up his wardrobe a bit.

Says The CW of Barry Allen’s first appearance in “The Scientist”:

A seemingly impossible robbery at Queen Consolidated’s Applied Sciences Division brings Central City police scientist Barry Allen (guest star Grant Gustin) to town. Citing a similar case back home, Barry offers to help Oliver (Stephen Amell) and team with the investigation. Oliver senses there is more to Barry than meets the eye, but he’s distracted by the similarities between this current case and something that happened on the island.

Meanwhile, Felicity (Emily Bett Rickards) takes a liking to Barry, which doesn’t go unnoticed by Oliver. Sin (guest star Bex Taylor-Klaus) asks Roy (Colton Haynes) for help when a friend of hers goes missing. Roy is surprised when Thea (Willa Holland) not only encourages him to help, but joins the search. Unfortunately, Sin’s friend is connected to Brother Blood (guest star Kevin Alejandro), and their search ultimately gets one of them seriously injured.

Keep in mind that Barry Allen's two-part appearance will culminate in a 'Flash' TV series pilot that may evolve into a full spinoff, though it remains to be seen if the character will return to 'Arrow' at all later in the season. In the meantime, check out Barry Allen in motion above, and give us your predictions for The Flash's big 'Arrow' debut in the comments!

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