She's Coming For You

She'd loved animals her whole life.

When her friends expressed their sadness that no one was hunting the hunters of animals, she decided to rectify the situation. She was the ideal candidate. In her normal job, as a soldier behind enemy lines, she'd killed animal abusers when given the chance and the animals were given some respite from their ordeals. 

Now she was not undercover. She was on holiday, travelling on the trains in Spain and Portugal.  

There were no colleagues to back her up. She would have to take risks. 

She doesn't keep a diary of the deaths, but does like to write about the history of the places she has visited. This makes her seem like a normal human being - even when she isn't.