“It was 7:35 a.m. and I was desperate.” From the opening sentence of Ear-Witness the territory is clearly defined. We are in the gritty, mean-street world of detective fiction. All the gumshoe conventions are here – the laconic tone, the telegraphic style, the tawdry settings, the precise accumulation of detail, the sidekick, the drugs, the sex, a good cop and a bad cop, even a final shoot-out à la Sue Grafton. How do these conventions translate into the young adult novel? In Mary Ann Scott’s hands, pretty well. The cans being popped are diet Coke instead of beer, the urban roaming takes place by public transport (“took the Queen streetcar as far as University”) and the squalor, sex, and violence are artfully muted.

Here’s the lowdown: Jessica March, 15, lives with her mother in Toronto’s Parkdale district. When their downstairs neighbour is murdered and Jessica’s mother’s boyfriend, Raffi, is accused of the crime, Jessica, who heard the event, turns detective. Fans of detective fiction tend to be two sorts: puzzle-solvers and snoops. Jessica reveals herself in a school book report to be the former sort, someone who enjoys figuring out the clues.

On this front Ear -Witness has a number of weak spots. The evidence against Raffi is insufficient for an arrest, the fingerprint clue is a bit obvious, and there is no real reason for Jessica to be in on the final shoot-out, especially not in disguise. But as a member of the snoop school of detective fiction readers, I care not a whit about these quibbles. I am just interested in snooping around in the characters’ lives. I don’t really care who killed the neighbour, but Scott did make me care about Jessica’s relationship with her too-busy mother, her anger at her absent lawyer father, her difficulties with her best friend, and about background characters such as the refugee family downstairs and the female police constable.

The writing is crisp and funny and the characters are real. Part of the pleasure of this kind of book is cumulative and I hope we see more of Jessica and the gang (preferably in a more congenial format; the oversize paperback suits neither the genre nor the audience). As for the plausibility factor – well, how many elderly tea-sipping grannies ever actually solve a murder either?