James McAvoy has teased 'Glass' is full of ''surprises''.

The 38-year-old actor is set to reprise his role as multiple-personality sufferer Kevin Wendell Crumb - which he first starred in M. Night Shyamalan's 2016 thriller 'Split' - who kidnaps Anya Taylor-Joy's character Casey as he attempts to battle his darkest personality known as The Beast.

The surprise ending of the film shows it be a follow-up to 'Unbreakable', which starred Bruce Willis as security guard David Dunn who discovers he has super-human strength and resistance to injury.

And while appearing on 'The Tonight Show Starring Jimmy Fallon', McAvoy said: ''There's an incredible cast. And, as always happens with [Shyamalan], it's just a really unexpected and strange turn of events that you wouldn't expect.

''You might think you'd know what's going to go on because you've seen 'Unbreakable', you've seen 'Split', but again it surprises.''

In 'Unbreakable', Samuel L. Jackson played Elijah Price, who was born with Type I osteogenesis imperfecta a rare disease that renders sufferers' bones extremely fragile and prone to fracture leading him to be dubbed 'Mr. Glass' by other kids and the inspiration for his search for Dunn's character, his polar opposite.

Price is revealed to be responsible for a number of terrorist atrocities orchestrated to find a real-life superhero.

In 'Glass', Dunn will be pursuing The Beast in 'Glass' in a series of encounters.

Ashwin Rajan and Marc Bienstock will also be part of the film along with Steven Schneider who will executive produce.

Recently Taylor-Joy, 21, admitted she ''completely died'' when Shyamalan told her she was going to be in 'Glass'.

She said: ''Night asked me to go to one of those tester screenings in Arizona.

''I went with him, and the ending wasn't part of that, but, as we were outside ready to go into the screening, [he] told me about it [and 'Glass'].

''I completely lost it. I thought, 'Man, that's so cool, like, you have to let me know how shooting goes!'

''He just looked at me and said, 'What makes you think you're not coming along for the ride?'

''I completely died. I was like, 'Wait, really? You want me to come and do this with you?' I was so excited to reprise my character, because I love Casey so much, and to be able to do it with all these unbelievable actors.

''I was at a table with all of these incredible people. I just thought, 'What the hell am I doing here?'''