Diana and her coven of druids cast a spell to bring Niall Oldman, the child of Merlin, to the 21st century. She informed him that she needed him to help her conceive a child, because she believed the child of Merlin would be powerful, and if the child was under her control, she would be powerful as well. Niall refused, until Diana told him the price of it: he needed to be sent back at latest on midsummer's day by midnight, otherwise he would immediately age and die. This information forced him to agree to her plans, but only begrudgingly. Diana then used magic to provide him knowledge of the modern times to help him fit in.
As the deadline neared, Niall secretly set out to find a parchment his father had left behind for him. Diana knew his attempts were futile—she had been keeping the parchment to herself the whole time. Near midsummer's day, she had her men kidnap an elderly woman named Bloodwen Jeffries as the sacrifice for the mating ritual. Niall met the Charmed Ones during this last week and recruited them in helping him. When the sisters used a spell to locate Merlin's scroll and Mrs. Jeffries, the spell showed them Diana's estate, but also unknowingly set off Diana's magical alarm. She then burned Merlin's scroll to leave Niall with no choice but to abide by her terms.
On midsummer's night, Niall met Diana's coven at their meeting place where the ritual was to take place. Niall distracted Diana while Piper rescued Mrs. Jeffries, then a fight broke out. Diana's coven quickly dispersed after witnessing the Halliwells' powers. Diana tried to fight them herself by drawing power from her magical stones, only to be defeated in the end.
- Piper was able to freeze her, theorizing that she was a practitioner since her magic came from two magical stones.
Diana Jones has appeared in a total of 1 non-canonical novel throughout the franchise.