Everything you need to understand or teach Something in the Air by Emma Lathen.
As always, John Putnam Thatcher lives, works, and detects in a world motivated primarily by greed. Though the characters of Something in the Air pursue money just as eagerly as their counterparts in the earlier books, Lathen makes an explicit connection here between money and power that in the past was more often implicit, or sometimes not mentioned at all. Thus the murderer acts out of fear that something he did many years ago will be revealed, and in the belief that by removing his blackmailer he can continue to suppress the past. The fact that his old crime was itself based on greed is entirely secondary, and no financial benefit can come from the murder.
In addition to the murderer, other characters in Something in the Air seek out and use power as an end in itself.
Phoebe Fournier, the outspoken representative of the Sparrow workers, uses...