When sisters, Nik (11) and Norva (13) discover the body of their Art Club Teacher in a skip on their estate they vow to solve the mystery of his death. Their investigation develops a speed and urgency when it points to their dad - the estate's premises manager - as a key suspect. The detective duo have a comic disparity: Nik (shaved head) is scientific, guided by facts and fond of drawing up lists, whereas Norva (long braids) favours intuition and the evidence of her feelings. The tower block estate, known as the Tri, is a diverse neighbourhood where a few idealistic individuals engage in community initiatives to improve its rundown facilities - a busy canvas for two nosey girls to scan through the telescope mounted in the window of their 22nd floor flat. As they vie with the police for leads, assessing the alibis and motives of various suspects, events move at dizzying speed, hypotheses unravel and new ones must be tested. This is a fun, engrossing read, despite its macabre premise, with much comedy in the characterisation and banter of the two sisters and their friends. With short sentences and snappy streetwise dialogue, the story races along, buzzing with exchanges of texts and emails as it accelerates to its exciting conclusion.