Neil McGrath is an officer in the Lothian and Borders police, described as a young man with short, dark hair. He is the younger brother of Ronnie McGrath, and was involved in the investigation into Ronnie's death.
Neil grew up in Stirling, several school years below his brother, who he claimed to know very well. When Ronnie left home, their parents never spoke of him and Neil lost contact with him. However through a friend of Neil's Ronnie wrote several letters describing his life in Edinburgh. After the letters stopped coming, Neil finished school (failing some of his exams) and joined the police force. He moved to Edinburgh, and was stationed at Musselburgh.
One night on his regular beat Neil found Ronnie on the street, heavily beaten and under the influence of drugs. He helped him home, and then the next morning went round to check up on him. He then visited him several times, trying to get him off his drug habit, avoiding Ronnie's friends. Their secrecy led Charlie, Ronnie's friend, to believe they were gay lovers. The last time Neil visited the squat was the night Ronnie was murdered. He didn't stay for long, just meeting with Ronnie upstairs and leaving, but dropped his tie clip on the landing near the stairs.
The next morning Neil hears the news of his brother's death, and notes that Rebus is heading the inquiry. He starts to tail Rebus, trying to pluck up the courage to explain Ronnie's story to him. On the tuesday night he witnesses Ronnie's girlfriend Tracy visiting Rebus's flat, but is chased away from the flat by Rebus. Then on the wednesday evening he follows Rebus to Ronnie's squat and goes in to talk to him. He explains why he has been following Rebus, and that he wants to help him catch Ronnie's killer. Rebus tells him he doesn't need the help.
However, the following saturday Rebus approaches him, having discovered that Ronnie was killed because of his involvement with Hyde's club. Neil agrees to help Rebus investigate the club by turning up drunk that night and causing a distraction. Him and 3 others are turned away from the doors of the club, but they provide the necessary time for Rebus to investigate and bring down the underground boxing club that caused Ronnie to be murdered.