Trying to remember a book I read in the 90s

[CanIhavedessertfirst]

It was a YA thriller where a teenage girl finds her mum's old diaries and comes to the conclusion her mum was involved in someone's death. I remember, at the end, she meets her mum from the airport.

[Dottierichardson]

OP now it's the holidays there are more posters around, so maybe someone will have heard of this, so bumping for you.