Watch Sky1's 'The Flash' and 'Arrow' crossover trailer

FlashSky1 has unveiled a new trailer for its upcoming US superhero series The Flash, a spin-off from its existing hit Arrow, which launched in 2012. The spin-off series centres on a socially awkward police forensic investigator called Barry Allen, played by former Glee actor Grant Gustin. After being struck by lightning in a freak accident, Allen awakes from a coma with super-speed, becoming "The Flash". The new trailer comes courtesy of our friends at Digital Spy, and sees The Flash crossover with its parent show as "The Flash" is seen training in a field alongside Arrow's Stephen Amell. Watch it below. Wentworth Miller has recently been cast in The Flash as a super-villain called Captain Cold – read more here. Meanwhile, the series is set to introduce two yet-to-be named gay characters during the course of its first season – find out more here. Arrow and Flash will both air on Sky1 in the UK, though exact premiere dates have yet to be announced.