Sian Brooke, known for her turn as Sherlock Holmes’ sister on BBC’s “Sherlock,” has landed a key role in the next installment in the “Mission: Impossible” franchise starring Tom Cruise.

Vanessa Kirby (“The Crown”) and Henry Cavill have also joined the cast. Rebecca Ferguson, Simon Pegg, and Jeremy Renner are also expected to return, though it’s unknown in what capacity.

Christopher McQuarrie, who directed “Mission: Impossible — Rogue Nation,” is back to direct this sixth film from a script he wrote.

It is unknown what Brooke’s role is, and plot details are also being kept under wraps at this time. Production is expected to start in the spring.

Cruise, McQuarrie and David Ellison are producing the film.

Brooke became well-known in the U.K. for her work on popular British television series such as “All About George” and “Cape Wrath.” Her recent stint as Holmes long lost sister on “Sherlock” caught the eyes of studio execs around town. Skydance and Paramount have been quick to land such rising stars as Brooke, as well as her co-star Kirby after she broke out on “The Crown.”

Brooke is repped by ICM Partners and Independent Talent Group.