Class Heroes is a series by Steve Henning, and while this novella takes place after books 1 and 2, it's self contained and can be read without knowing what's happened in those stories.
Lolly is on the run. She has arrived in London, penniless, alone and – worse still – she has lost her fearsome superpowers.
She is being hunted by the police and the Security Service. She has
no friends and very few people who would want to help her. She needs
money and a place to lie low, while she formulates a plan to rescue Sir
Michael Rosewood, her father. He is being held prisoner by the British
Government at a secret location.
There is one person who may just agree to help Lolly. An old friend
of her father. However, time is running out because the Security Service
are hot on her trail...
I've read the first two books and they're quite fun. This novella is on my to be read pile. Here's where you can get the eNovella, today*, for free:
* At the time of posting all the links had the book listed for free. Check before buying to confirm that's still the case.