As a child, Yasmin attended Redlands Primary alongside Ryan Sinclair. Years later, she joined Hallamshire Police as a junior officer. As a trainee on second-year probation, Yaz was often sent by her superior, Ramesh Sunder, to deal with small-time petty disputes. After vocalising her need for something more, she was sent to investigate an unidentified object in the countryside outside Sheffield. There, Yaz found the caller was Ryan Sinclair, whom she recognised from school. Ryan insisted the call was not a prank and, though Yasmin didn't initially believe him, touching the cold object lead to her doing so.
After Ryan received a call from his grandmother, Grace, Yaz accompanied him to check on her, finding her train under attack from a mysterious creature. There, she encountered the Thirteenth Doctor. Yasmin, along with Ryan, Grace and the latter's husband Graham O'Brien, helped the Doctor investigate and stop the pod's occupant, a Stenza named Tim Shaw, from abducting Karl Wright. After Grace died while disabling the coil, Yasmin attended her funeral.
Yasmin later helped the Doctor construct a teleporter to get her to her TARDIS. Though meant to stay whilst she left, Yasmin, Ryan and Graham were also teleported into deep space with her. (TV: The Woman Who Fell to Earth)
Yasmin was ambitious. Although outwardly confident, she wasn't overly so, and was aware that she still had much to learn; she once exclaimed "Isn't everyday a learning day!" while attempting to control a crane. Her police experience meant that she was a good negotiator, capable forming a truce between two opposing civilians. (TV: The Woman Who Fell to Earth)