Kick-starting the action … violence takes place in Dead Ends when people are 'asking for it'. Photograph: Jonathan Hordle/Rex Features
Erin Lange's subject is bullying. In her debut novel, Butter, we were on the side of the victim, a fat boy attempting to eat himself to death on the internet for the grisly viewing pleasure of his peers. In Dead Ends, we are rooting for the bully – hot-headed thug Dane Washington, who kick-starts the action by unapologetically smashing his foot into "some guy's throat". In Dane's world, violence is justified if people are "asking for it", the only exception to the rule being girls and "retards".
If you balk at the use of that word, Dead Ends is not the novel for you. Like RJ Palacio, with whom Lange has been compared, she pulls no punches when describing the mistreatment of "freak" Billy D, a teenage boy with Down's syndrome, who moves into Dane's street on the wrong side of town (Columbia, Missouri). At best, Billy D is seen as a helpless victim in need of mollycoddling by the well-meaning but patronising staff of Twain High School; at worst, he is "Flat Face", teased for his slack jaw, slanted eyes and lisping, high-pitched voice by a group of seniors threatening to beat him up for being different.
This is exactly the type of cruelty that righteous hardcase Dane cannot stand ("standards, y'know?"), but that does not mean he is keen to befriend "Special Ed" himself; entertainingly, he is blackmailed into it by Billy D, who realises a tough guy like Dane could be a handy ally:
"My next-door neighbour Mark calls you that dick," Billy D says, when Dane refuses to reveal his name, "but [...] I know what a dick is, and it's not a name. In my life-skills class, they call it a penis."
"I don't want to talk about dicks with you," replies Dane, in typically irritable fashion. He is no clear-cut hero and Billy D no flawless victim: Lange is too good for that. Both boys are fully-fleshed individuals with the capacity to amuse, delight and infuriate, and we teeter deliciously between loving them and wanting to bang their heads together in exasperation (especially towards the end of the novel, where there are a few too many arguments between the pair for my liking). Over time, the boys become real friends, though there is no sentimental softening of Dane's character, even though he learns a good few lessons along the way. Throughout, his gruff treatment of Billy D strikes the perfect balance between tough and tender, clumsy and kind. He gets it wrong. He is politically incorrect. But he cares.
That's why he agrees to help Billy D find his father, whose mysterious whereabouts are believed to be hidden in a series of clues scribbled in an atlas. Sound bizarre? I thought so, too. The treasure-hunt-style search for Billy D's dad didn't quite work for me. The endless deciphering of the riddles felt repetitive and frustrating as the boys hit dead end after dead end. More satisfying by far was the bond they shared due to their absent fathers, their anger and prickly vulnerability sensitively portrayed by Lange.
There's a road trip, a love interest, a clever twist and an ending that offers just the right amount of closure without tying up all the loose ends in a too-neat bow. The ingredients for a great story are all present, and most of them come together beautifully.
• Annabel Pitcher's latest book is Ketchup Clouds (Indigo).