The Janus Affair is the second book in the humorous Ministry of Peculiar Occurrences steampunk series. Archivist Wellington Thornhill Books and his junior assistant, former field agent Eliza D. Braun, are again investigating peculiar occurrences against the will of their superior, Doctor Sound. The Janus Affair starts about a year after the end of the previous book, Phoenix Rising.

Wellington and Eliza are returning from a Ministry trip in Scotland when a young woman vanishes in a blinding burst of electricity before their astonished eyes. Eliza knows the woman: she's one of the key figures in England's Suffragette movement. To Eliza's annoyance, the case is given to a field agent whom she loathes and suspects of incompetence.

Soon Eliza notices that other women in the Suffragette movement are also disappearing in the same manner, but for some reason the Ministry is not investigating the matter. Then her mentor, Kate Sheppard, who is the leader of the New Zealand Suffragettes, arrives in London and asks Eliza to protect herself and the other women. Eliza digs in and drags Wellington kicking and screaming with her. But Eliza's first love has also come to London: Kate's son, Douglas, who wants to renew his relationship with Eliza. At the same time she has to confront her past, Wellington has to face his growing feelings for Eliza.

The Janus Affair has a fast moving plot and many delightful characters. Eliza Braun is a woman with strong opinions and good aim, and the events of this book put her bulletproof corset and collection of weapons to the test. Underneath her tough exterior, she has vulnerable spots; Wellington is one of them. His restrained and proper exterior hides secrets only hinted at in the previous book. Wellington loves to build things, and his cellar is full of various technological gadgets. He enjoys solitude and wants to follow the Ministry's rules, unless Eliza can convince him that they need to bend them.

Douglas Sheppard is Wellington's opposite: an adventurer almost as brash as Eliza. It is inevitable that when Douglas appears, Wellington must acknowledge his growing feelings toward Eliza and wallow in jealousy.

The children who help Eliza, the Ministry Seven, almost steal the show. This precocious group of street urchins, accustomed to taking care of themselves and fiercely loyal to Eliza, are skilled pickpockets, actors, and burglars. They're masters of conning other people, and they have a lot of information that Eliza and Wellington need. Eliza also truly cares about them. Eliza's maid servant, Alice, is also an eccentric character. Eliza encourages Alice to speak her mind when she is with Eliza and Wellington. Alice's previously injured legs have been replaced with hydraulics, and the prosthetics hide an impressive amount of weaponry.

Some of the villains from the previous book return: Sophia del Morte, an assassin and worthy foil to Eliza, is working for the mysterious Maestro. In turn, the Maestro can threaten even the Duke of Sussex to do his bidding.

The steampunk technology is better integrated into the society this go-round. Eliza is also not the only woman doing things in defiance of Victorian society, so things seem to have changed for women (for example, there is a whole gang of female criminals in London). The Janus Affair also explores a little of the sexism that Eliza and other women deal with on a daily basis, but the main focus is on humor and high adventure.

The Janus Affair is fun, lighthearted steampunk with delightfully eccentric characters.