Doctor WhoJust Threw Everyone a Heck of a Curveball

The novel season ofDoctor Whois in full swing music , and it ’s already make some big moves early into its run . This week ’s installment , “ Boom , ” cast theDoctor and Rubyon the major planet of Kastarion 3 , which is presently in the midst of a war the duad are unable to escape from after the Doctor is trapped by an active landmine . That does n’t stop them from name Friend amidst the conflict , though — in fact , one of the allies they gain made for quite a pleasant surprise .

Anglican Marine Mundy Flynn , who helps the Doctor and Ruby throughout the episode , is played by Andor’sVarada Sethu , who ’s set to be the new ( and currently unknown ) companion in the next season . It appears Sethu wo n’t reprise the role when she comes over full - time , something made clean-cut onTwitterwhen she mouth about taking her first steps into the franchise through Mundy . “ I ’m so thankful I get to come back for more , ” she wrote , “ but you ’ll all have to wait and see how that attest in the new fellow role . ”

Talking to theHollywood Reporter , installment writer Steven Moffat wasequally tight - lipped on how her double casting came about , and deferred to Sethu ’s appaearance here as all part of showrunner Russell T. Davies ’ plans . However , he did note there was some fun in doing a classic Who casting move of hire invitee actors who end up playing companion down the line . In the modern Who geological era , it happened to both Freema Agyeman and Jenna Coleman — the former ’s guest theatrical role was later on made into the cousin to eventual her companion office of Martha Jones — and even Peter Capaldi down a Edgar Guest part before he ended up becoming the Twelfth Doctor .

Image: BBC

Sir Humphrey Davy reaffirmed Sethu ’s statement that Mundy ’s story has come to an death , and that her fellow traveller reference will be revealed in full next year . Whether you conceive him or not , her usher up helped make the instalment even more exciting , and it make the waiting for her to hang with the Doctor and Ruby feel even longer .

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Graphic: Jim Cooke