The plot plays in London in the late 19th century - the prudish Victorian era. In these times many women were falsely diagnosed with an alleged disease called "hysteria" as a response to symptoms like nervousness, insomnia, exhaustion, depression, cramps, and sexual frustration (wikipedia). Wikipedia claims that many physicians tried to cure "hysteria" by massaging the most sensitive parts of their female patients with their hands (in Germany the films runs with the title "In guten Händen"/"In Good Hands").
The movie tells the story of a young doctor and his employer who used this then popular method with a lot of success and made good money with their growing crowd of satisfied customers. Unfortunately the rising demand lead to a kind of manual assembly line job which got more and more tedious and exhausting. But then "came" help. An inventor friend of the young doctor developed a mechanical device - driven by electricity produced by a huge crude machine - which completed the same task quite satisfying.
Don´t expect sex scenes. You won't get them. Instead Tanya Wexler, the director, deals with this delicate topic in a comical manner and created a lot of funny situations and dialogues which cause plenty of laughs. The cast is part of the fun, especially Rupert Everett as a wealthy faineant and genius inventor. Maggie Gyllenhal, playing a suffragette, overacted a bit, but did still a nice job. But my favorite actor was the technological construction. If you stay till the credits you can the see the evolution of this device over the following decades. A praise to the technical progress!