YA Suspense book. I think main character is a girl that moved house somewhere, towards end of the book she end up going through a hidden passage or tunnel and brother with mask appear

[Aj]

I read this between 2012-2014 from my secondary school libary
The girl moves house maybe to step family think its set in October time possibly.
A part where shes in coffee shop or car park and mysterious guy maybe step bro
Then end she goes through secret passage in house and the step bro follow or appear

[Rainbowheart]

Do you think it was a British book?

Was the girl a teenager or a younger child?

[Aj]

I think so, she was a teenager I'm sure