'The Flash' Spoilers: Secrets Will be Revealed During 'Arrow' Crossover!

Grant Gustin bundles up in a zip-up hoodie and warms up with a coffee while on set of The Flash on Sunday afternoon (November 9) in Vancouver, Canada.

The 24-year-old actor and the cast are gearing up for the big crossover episode with Arrow, which airs Tuesday, December 2.

Click inside for spoilers about the episode, and 10+ pics…

“We discover something about Oliver (Stephen Amell) which is probably one of the biggest secrets we’ve ever revealed on the show – and it happens on The Flash,” executive producer Andrew Kreisberg told TVGuide.