Red Herring Highway
The Move the Motorway campaign is one of the novel's red herrings. A highway is going to be built through Knocknaree, and some people don't want it, because the historic woods will be bulldozed in the process. They don't want the highway gone, per say, they just want it moved, like, a few feet to the right. But according to Mark, "the government doesn't give a f***" (6.43). This happens with governments.
Jonathan Devlin heads up the Move the Motorway campaign, which makes him a target, and the police briefly suspect one of the developers or landowners might have hired an assassin to kill Katy as a threat against her old man.
The motorway may be a red herring, but it ties into the setting, particularly the economic despair prevalent in Knocknaree. Sam defends the motorway, saying, "The motorway will do a lot of good, Cassie. […] There'll be new houses, new jobs" (8.24). But of course Sam thinks this—his uncle is in charge. The economic benefit, at this point, is all speculation, and because of this, the highway reminds us of the downtrodden community this murder takes place in, keeping the bleakness of the book alive and kicking.