Leeds August 1914. When the Lamps Went Out is the first in a series of cases for home front detective Frank Marvell. On the night war is declared and celebrations follow it soon transpires that a German immigrant has been murdered. Possibly connected is Oswald Wiseman, a charismatic anti-German rabble-rouser with a large estate on the edge of the city. Marvell, who's assigned the case, is already investigating damage to Wiseman's mother's grave, whose unusual sculpture intrigues him. The case poses many challenges for Marvell, who is all the while wrestling with personal issues. Estranged from his suffragette wife, he is burdened with an elderly mother and a conscientious objector son. He is also harassed by the deranged Horace Sides, a man with a grudge bent upon a showdown. If this isn't enough to contend with, Marvell's superior seems to be playing a double game by secretly visiting Wiseman's mansion. Also on the scene, for reasons yet unclear, is an agent from London's Special Branch. All is eventually revealed, and it's far more sinister than anyone supposed.