As Prime Video’s 'Citadel' races towards its finale on May 26, it has been making waves across the world, with one of the largest global audiences in the history of Prime Video tuning in weekly for the latest episodes of the action-packed spy series.

Talking about the expanse of stunts and the train sequence that got us to the edge of our seats, Richard Madden shares, “It was a complicated process getting ready to actually shoot [episode one’s] train sequence because we had all of the confines of being in a small space. And we worked really closely with this amazing stunt team to work out what are our strengths, be it speed or agility, or brute force… and how we could incorporate them into this space. So we managed to get into the studio before we started filming and started learning a language of footwork and gunplay. How do we incorporate all of these things there? Okay, we've got a shotgun, but how can we use it as a sword? How can I use it as a battering ram? How can I load it and throw it so the other actor can fire it? So, they were really plugged into the heart of what Nadia and Mason are, which is two people that can work beautifully together to make one super weapon.”