In the strangest bit of casting you're likely to hear today, Neil Patrick Harris has signed on to star in The Matrix 4.

The How I Met Your Mother star will join the returning Keanu Reeves and Carrie-Anne Moss in the sequel to the sci-fi film trilogy, which is set to go into production in early 2020, over 16 years after the third instalment was released.

Details about Harris' role are being kept under wraps for now, and we are still none the wiser as to the plot of the film. Laurence Fishburne, who played Morpheus in the original trilogy, is still conspicuously absent from all of this, with rumours suggesting that a younger actor will be scouted to take on his role.

Harris is no stranger to dramatic cinema, having starred alongside Ben Affleck and Rosamund Pike in David Fincher's Gone Girl in 2014. But this role - in a self-serious action blockbuster - nonetheless represents a major jump for the actor, who has recently been seen Netflix's A Series of Unfortunate Events and Alexander Payne's Downsizing.

Keanu Reeves The matrix
Keanu Reeves (Warner Brothers)

Jada Pinkett Smith is reportedly in talks to reprise her role as Niobe, according to Deadline. She played the character in The Matrix Reloaded and Matrix Revolutions.

One half of the original director duo, Lana Wachowski, has signed on to write, direct and produce the film, despite its lead character Neo (Reeves) having apparently died at the end of Matrix Revolutions.

It'll be interesting to see how this one turns out...