LONDON (AFP) - M. Night Shyamalan is offering a two-in-one deal. Known for his film-ending twists, the director on Wednesday (Jan 9) took his latest offering to London - thriller Glass which taps two of his past movies.

Starring Bruce Willis, Samuel L. Jackson and James McAvoy, Glass blends storylines from Unbreakable (2000) and 2016's Split.

Shyamalan said at the London premiere: "It was almost like I didn't want to make it for 15 years and then started to open my mind up to 'hey, you know, let's go back to those characters and finish telling those stories'."

Willis and Jackson, who both starred in Unbreakable - about a train crash survivor who discovers he has a new superpower - were joined at the screening by McAvoy, who played Kevin Crumb, a man with multiple identities, in Split.

In the new film, Willis reprises his role as a security guard who chases one of Crumb's frightful personalities.

Jackson, who returns as the fragile Elijah Price, said: "I always thought Elijah was unfinished business. Night promised that it was part of a trilogy so this is closure."

McAvoy revisits his role as well as his character's multiple personalities.

"I love acting so getting to do more of it is not a bad thing but you've to do a lot of preparation... it was like cramming for an exam that you forgot was coming."