‘Arrow’ “The Scientist” Preview: Producers Tease Barry Allen’s Arrival, Plus Alex Kingston to Return!

The CW's 'Arrow' will soon enter a brave new world of DC tie-ins with this Wednesday's "The Scientist," bringing forensic scientist Barry Allen (Grant Gustin) into the mix to investigate a seemingly superpowered crime spree. To that end, the CW has flashed on an in-depth new preview for the hour, along with news that 'Doctor Who' star Alex Kingston will return as Dinah Lance!

First things first, Barry Allen's arrival will coincide with an impossible series of robberies that Oliver Queen (Stephen Amell) looks into, as we see the youthful comic book-toting scientist making his way to Starling City to answer the call. Allen's chemistry with Felicity (Emily Bett Rickards) proves electric in the above clip, even as Barry jokes that he's "not too good on his feet."

Says The CW of Grant Gustin’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.

Elsewhere, TVLine has learned that season 1 guest star Alex Kingston ('Doctor Who'), will return in her role as Laurel's mother Dinah Lance, though details on the appearance are light for the moment. Presumably, Dinah's return will play on the fact that her daughter Sara Lance (Caity Lotz) was revealed to be alive after all, though her father Quentin swore to keep the secret, lest the "League of Assassins" target them.

What do you think? Will the first of 'Arrow''s two-part midseason finale "The Scientist" live up to the hype? Will more of the Lances discover The Canary's true identity? Check out the producer's preview above, and give us your predictions in the comments!