The jacket controlled whoever wore it.
Jen didn't know that when she found the jacket at the antiques store.
The jacket also gave you what you wanted.
That is why Jen didn't really know what the jacket was doing to her.
Because if she did wouldn't have killed the owner of the antiques store.
Marie
She sold the jacket to her. she didn't know until after Jen left.
After the owner of where she works get murdered, she knows who did and needs to get the jacket back.