British actor Eddie Redmayne, who played the role of the late Professor Stephen Hawking in the 2014 biographical drama The Theory of Everything, attends his funeral at University Church of St Mary the Great in Cambridge, England, Saturday March 31, 2018. Picture: AP

Eddie Redmayne says 'Fantastic Beasts: The Crimes of Grindelwald' is "darker" than the first instalment.

The 36-year-old actor is set to reprise his role as magi-zoologist Newt Scamander in the upcoming sequel to 2016's 'Fantastic Beasts and Where to Find Them', and has said the second movie takes the franchise down a much more "cryptic" route.

Speaking about the movie - which is a spin-off of the 'Harry Potter' franchise - Eddie said: "The most riveting aspect is the tonal change. It's darker and more rigorous and weaving in the 'Potter' lore we're much more familiar with. So these characters you met in the first film are now in the wizarding world you understand more thoroughly. When I read [the script] it had these cryptic elements to it and it played like a thriller that made it a page-turner."

Eddie also teased a few new hints at the story of the second movie, which sees dark wizard Grindelwald (played by Johnny Depp) escape after being sent to Europe to be tried for his crimes in the first movie.

He told Entertainment Weekly magazine: "I'm enlisted by Dumbledore (Jude Law) to try and track him down and capture him. What's happened is Grindelwald's belief that purebloods should reign over all non-magical beings is a political thing. He's rallying more and more people and it causes divisions across families. He's pretty hypnotic."

Meanwhile, Eddie won't have long to wait before he's stepping into Newt's shoes for the third time, as 'Harry Potter' author JK Rowling recently revealed she has already begun writing the screenplay for the third 'Fantastic Beasts' instalment.

In a Q&A on her own website in June, Rowling shared: "I've just finished the fourth Galbraith novel, 'Lethal White', and I'm now writing the screenplay for 'Fantastic Beasts 3'."

'Fantastic Beasts: The Crimes of Grindelwald' is due to hit cinemas in November.