Gate Sinister. Sparks and Philtres, #1

Disguised as a governess, the last fairy in Britannia infiltrates the household of the Gloucester family to fulfil a vital mission on behalf of her exiled people. On the run after offending the Royal family, two infamous magical engineers set out to commit the crime of the century on behalf of a wicked enchantress. For one night only, the Gate Sinister can be opened between worlds, clearing the way to the long-lost Forest of Arden.
For one night only, all things are possible.The first in a new gaslamp fantasy series of novellas by the author of Tea & Sympathetic Magic and The Frost Fair Affair.