Among the Mad

In the sixth entry in the series, Maisie must deal with the lingering effects of WW1 trauma. After narrowly escaping death herself when a despondent war cripple commits suicide, she becomes an adviser to Scotland Yard Special Branch.
The main story is about a wounded (emotionally and physically) WWI veteran who is threatening to release poison gas in London. First he poisons animals, then targets members of the government, and finally threatens the general public. With a New Year's Eve deadline, a pulse-pounding manhunt is on. Though Maisie prefers to work alone, she must coordinate with Special Branch and also deal with a shadowy government agency that seems to dog her every step.
There are sub-plots also. Maisie's assistant, her best friend, and even Maisie herself must also deal with their own lingering traumas. Winspear deftly meshes these elements with the main plot.
Pretty good book. One of the best in the series to this point.