Lena Headey is set to star in new assassin movie 'Gunpowder Milkshake'.

The 45-year-old actress is joining the new thriller from Studiocanal and The Picture Company, and the 'Game of Thrones' star will star alongside Karen Gillan, who is expected to be the lead of an all-female cast with filming due to begin in Berlin, Germany, in the spring.

Although details of the plot have been kept under wraps, the film is described as being in the assassin genre and includes stories spanning over multiple generations.

The action flick will be directed by Aharon Keshales and Navot Papushado, the pair responsible for the dark Israeli breakout 'Big Bad Wolves' and the duo also penned the script alongside graphic novel writer Ehud Lavski.

Andrew Rona and Alex Heineman of The Picture Company will produce the movie through their overall deal with Studiocanal.

Lena recently wrapped up her final scenes as ruthless Queen Cersei Lannister in HBO fantasy series 'Game of Thrones', which premieres in April, and the star previously admitted that she was overcome by emotion during her last days on set.

Lena - who made her 'GoT' debut in 2011 - previously confessed: ''I knew that David [Benioff] and Dan [Weiss], our creators, were doing speeches and giving everybody these drawings of the storyboards.

''And I suddenly got really emotional at the end and tried to head down the stairs. They all rushed up and trapped me. And then they gave the speech, and it was really moving.''

The '300' actress also revealed that - much like the show's fans - the cast are always keen to discover how the story will evolve.

The actress - who stars alongside the likes of Sophie Turner and Maisie Williams - shared: ''They usually give us all of [the scripts], and if anyone says they don't flip to the end, they're lying.''