Downey Jr. is back in Joss Whedon's sequel as Tony Stark/Iron Man. This time, Tony is responsible for jeopardising the entire world when his new peacekeeping programme goes awry. How awry? Well Stark's creation, sentient robot Ultron (voiced and performed by James Spader), looks to turn the Avengers against one another and obliterate humanity in the process.
"Tony's Ultron defence system is supposed to let everybody retire," he explains. "As far as Tony's guilt, I think it's always tougher when you had a pure heart going in. I think that's the rough part."
Apart from the dramatic-sounding Ultron storyline, the film is also generating excitement for how it anticipates the forthcoming Captain America: Civil War, due out in 2016. In the latter, Iron Man finds himself pitted against his former compatriots, and we get glimpses of his brewing conflict with Bruce Banner/Hulk (Mark Ruffalo) in the Age of Ultron trailer.
Downey Jr. says this will take the character in exciting new direction. "It's natural to change your views," Downey Jr explained. "The main thing to me is - and this is where I think the Russos [Anthony and Joseph] are quite brilliant and where Kevin [Feige] backed the play - what sort of incident could occur and what sort of framework could we find Tony in? The clues are in Ultron about where we might find him next."
Consider us sold. Avengers: Age of Ultronhits Cineworld on 24th April.