Lucas by Kevin Brooks is a terrific read which I zipped through in a couple of days. Notionally aimed at ‘young adults’ it’s more than suitable for older adults as well!
It’s told by a 15 / 16-year-old girl, covers all the relationships you’d expect (friends, parent, brother), deals with matters of grief and responsibility, and finally develops into a tense thriller.
A well-written and easy to read novel, it’s highly recommended.