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Doctor Who was set to embark on a new era. The long-standing British sci-fi series finally secured a global partner in Disney, and it launched a fresh start with a new (yet returning) showrunner, a new lead actor, and . But what was meant to be a completely new installment ended up being just a brief chapter.

Following Season 2, Disney chose not to extend the partnership, which has thrown the . But what plans were in motion before this crushing decision? A recent report indicates the series was poised to resolve a mystery that’s over 50 years old.

Susan Foreman, the Doctor’s granddaughter, was the first-ever Doctor Who companion as we know it. | BBC Studios

Per , pre-production for Season 3 of Doctor Who was already underway when the Disney announcement led star Ncuti Gatwa to depart, requiring the ending to be re-shot to depict the Doctor’s regeneration. But it seems the original ending would have been precisely what fans have been begging for. “Months after filming concluded, the cast and crew returned to set to film Gatwa’s regeneration,” the report states. “The original Season 2 ending—featuring Carole Ann Ford reprising her role as the Doctor’s granddaughter and first companion, Susan—remains unreleased.”

Though this source is still unconfirmed, it aligns with everything we’ve seen in Doctor Who up to this point. Season 1’s second-to-last episode introduced Susan Triad (Susan Twist), whom the Doctor believes is his granddaughter, Susan Foreman. That turned out not to be the case, but the mystery surrounding Susan persisted.

A now-older Carole Ann Ford returned as Susan Foreman in Season 2 of Doctor Who. | Disney+

Most fans had abandoned hope of getting answers about Susan. The character remained on the series only until the 1964 story “The Dalek Invasion of Earth,” where she fell for a freedom fighter and bid her farewells. However, Season 2 was packed with nods to her, such as a short cameo in “The Interstellar Song Contest” and “Wish World.”

Had it not been for this eleventh-hour change, we might have actually tackled this plotline and solved a mystery that’s haunted the Doctor Who fanbase for decades and across multiple regenerations: what really happened to the first companion? It’s yet another casualty of a decision by those in charge, but there’s still a chance it could be explored in whatever future iteration Doctor Who takes.

Here’s hoping it doesn’t take another 60 years to revisit Doctor Who and the mystery of Susan.

Doctor Who Seasons 1-2 are now streaming on Disney+.