EntertainmentTVSci-Fi ShowsDoctor WhoYes, that is Doctor Who’s new season 2 companion in Boom – but the mystery cameo leaves us with more questions than answersWhen you purchase through links on our site, we may earn an affiliate commission.Here’s how it works. EntertainmentTVSci-Fi ShowsDoctor WhoYes, that is Doctor Who’s new season 2 companion in Boom – but the mystery cameo leaves us with more questions than answersWhen you purchase through links on our site, we may earn an affiliate commission.Here’s how it works. When you purchase through links on our site, we may earn an affiliate commission.Here’s how it works. (Image credit: BBC) Some spoilers forDoctor Who episode 3follow. You have been warned. ‘Boom’ was an instant classic: a nerve-shredding, landmine-stepping trip to a planet caught in the middle of a never-ending war. Sethu is all set to be the Doctor’s next companion in the second season of the BBC/DisneyPlus series. So why has she shown up early? Honestly, it’s not quite …