The Hanging Shed by Gordon Ferris

Glasgow, 1946: The last time Douglas Brodie came home it was 1942 and he was a dashing young warrior in a kilt. Now, the war is over but victory's wine has soured and Brodie's back in Scotland to try and save childhood friend Hugh Donovan from the gallows. Everyone thought Donovan was dead, shot down in the war. Perhaps it would have been kinder if he had been killed. The man who returned was unrecognizable: mutilated, horribly burned. Donovan keeps his own company, only venturing out for heroin to deaden the pain of his wounds. When a local boy is found raped and murdered, there is only one suspect...
Donovan claims he's innocent but a mountain of evidence says otherwise. Despite the hideousness of the crime, ex-policeman Brodie feels compelled to try and help his one-time friend. Working with Donovan's advocate Samantha Campbell, Brodie trawls both the mean streets of the Gorbals and the green hills of western Scotland in their search for the truth. What they find is an unholy alliance of church, police and Glasgow's deadliest razor gang, happy to slaughter to protect their dark secrets. As time runs out for the condemned man, and the tally of murdered innocents rises, Brodie reverts to his wartime role as a trained killer. It's them or him.

This book is part of the "Douglas Brodie" series.
Here are some other books from this series: