Lachlan Mackintosh is the school history teacher in the Edinburgh pre-university college.

He is locked in a custody battle for his six-year old son with his soon to be ex-wife, Lisa. She has moved to Aberdeen with her new boyfriend. The affair had been going on for nearly a year before Lachlan found out. The culprit was his former friend from training college, Scott Tenormann.

Lachlan is haunted by a tragedy that happened when he was a trainee teacher. While taking a school trip hiking in the Scottish highlands a boy died from exposure when he was sent at dusk to collect firewood as a punishment for playing up during the day's walk. Lachlan forgot the boy was out and so a search party was not dispatched until the morning. The child was found dead; he had fallen in the dark down a hillside and broken an ankle. The cold night claimed him, lost, terrified and alone. The boy, James Campbell, was eleven.

Lachlan maintained that he had gone out with a flashlight looking for the boy but did not alert the other children at the time, so as to avoid a panic. This was not true as it was early in the morning before he remembered the boy had not returned. No one actually knows the truth (except Scott suspects?).

Since his wife left he has been half-heartedly competing for the attention of the school home economics teacher Julie Winthorpe with Grant Buchanan – the metal work teacher. Lachlan is not very good with women in general and so does not seriously think he has a chance, especially since much of his time and money is presently being used up on the custody battle and trying to appear to be a stable parent.

His solicitor is a bit of a prick, but an old acquaintance: Sam McBride.

His best friend (or the closest to it) is a fireman, Tony Wood, originally from Wolverhampton. He is a nice guy with a young family and effectively has everything that Lachlan had, but lost. Tony is a devout Christian and originally introduced Lachlan to the Church. They are neighbours.

One of Lachlan's students, Sally Benfield (17) is also a member of the Church. She has had a tough time at home and finds support in the church group. Her father is a violent drunk. Lachlan feels responsible for her and tries his best to keep the relationship platonic.