[s4e1] Partners In Crime -

But the reunion was cut short. Miss Foster wasn't just selling pills; she was using London's population as a surrogate nursery. With a flick of a remote, the "miracle" began. Across the city, thousands of tiny, marshmallow-like creatures—the Adipose—began to spontaneously generate from people's stored body fat. They were cute, sure, but the process was lethal if fully completed.

"I'm not staying," Donna said, though her eyes were already fixed on the horizon. "I've got a car, I've got a life... but I've also got my bags in the boot." [S4E1] Partners in Crime

The breakthrough came in the office of Miss Foster, the "nanny" behind the miracle pill. The Doctor was hiding behind a gurney; Donna was crouched behind a desk. As Miss Foster began her villainous monologue, the Doctor looked up, and Donna looked across. Through the glass of two separate doors, their eyes met. But the reunion was cut short

The Doctor grinned, snapping his fingers to open the doors. After a missed chance and a long search, the girl in the wedding dress had finally become the partner in time. "I've got a car, I've got a life

As the spaceship loomed over the skyline, Miss Foster learned the hard way that "Partners in Crime" is a dangerous title to hold with the Doctor. Once the Adipose were safe, the parent ship disposed of the evidence—Miss Foster herself—leaving the Doctor and Donna standing on the rooftop. The TARDIS sat nearby, its blue door a standing invitation.