The Apparition Phase by Will Maclean
Their trick certainly works - Janice believes their ghost is real. But when Abi and Tim explain what they've done, Janice doesn't change her mind. And then tragedy strikes the Smith family and the twins' lives are changed forever.
In Tim, Will Maclean gives us a narrator who is looking back on the events of his youth with the benefit of hindsight, which means he's capable of analysing his own teenage behaviour, but just how reliable is Tim's account of what happened? The relationship between Tim and Abi is an intense one, to the extent where they don't really have any other friends, so when Abi, the more dominant personality, starts to drift away a little, there's already a sense of Tim being left behind at the point at which his life is torn apart.
The latter half of the book, in which Tim, now an older teenager, becomes involved with a group of paranormal investigators staying at an old mansion house, feels quite different to the earlier chapters, and yet it's certainly no less creepy. Once again, Tim is the outsider, patronised by the academics and lacking the class advantages of the others to the extent that they nickname him 'Comprehensive'. There's a simmering tension among the group, confined together during a hot summer, which is almost worthy of a psychological thriller in its own right. Are the strange disturbances in the house really supernatural, or are they the inevitable consequence of gathering a group of damaged teenagers into a highly-charged environment and putting them into nerve-jangling situations? Certainly, most of the adults in The Apparition Phase are at best negligent and at worst deliberately manipulative towards the young people in their care.
This is a book that manages to cram an awful lot into its pages. There's a sense that there's more than one story being told here, and yet it always feels cohesive. It's atmospheric and evocative, with all the right hauntological notes of nostalgia and eeriness, and Tim as a protagonist is both ambiguous and convincing. This is a strong, intelligent sensitively written ghost story and most importantly, a genuinely unnerving one.