Robert Pattinson has joined 'Lost City of Z'.

The 'Twilight' hunk has signed up alongside Benedict Cumberbatch in James Gray's new film, based on David Grann's non-fiction book documenting Amazonian explorer Percy Fawcett's deadly obsession with discovering a lost city in the rainforest.

It is believed Cumberbatch will play the leading role of Percy Fawcett, but it is unknown what Pattinson will play.

Fawcett disappeared in 1925, along with his son, after trekking through the Amazon to gather evidence to support his claims a mysterious city, which he dubbed the Lost City of Z, existed within the heart of the rainforest.

The film will be produced by Brad Pitt through his Plan B company, along with Dede Gardner, Jeremy Kleiner and Anthony Katagas.

Pitt has reportedly been developing the project for several years and at one point even considered starring in the movie himself.

Meanwhile Pattinson is currently involved in the upcoming film 'The Rover', which will see him play a man forced to leave his family behind as he embarks on a revenge mission with an injured gang member.