The premise is that the protagonist of The Dulwich Horror, Jessica, has been cast back into time. It is a pulpy adventure that takes place in a pre-Bronze Age Stone Age civilization. References are made to A Conneticut Yankee in King Arthur's Court and the Barsoom novels with a joke that the protagonist, Jessica, isn't like any of those supermen with their knowledge of engineering as well as military tactics.
Jessica is a Edwardian woman who finds herself soon the head of a time-lost band of women who are all of varying ethnicities. They avoid becoming the property of the local tribes due to some fast thinking and the belief they're goddesses. They have an enemy in the Spawn of Cthulhu, however, who threaten to wipe out humanity before it can ever become a threat to even the lowliest of his servitors.
Much is made of Jessica trying to survive in a time without any form of metallurgy, hygeine, or amenities. It is also a work with a feminist slant as the women band together to try to assert their dignity. It is also a adventure about slaying prehistoric eldritch monsters. I liked the latter element a lot more and note this is a very Pulpy Conan-esque view of the Bronze Age and almost wish he'd gone full Howardian.
David Hambling has an engaging and entertaining writing style as well as a fascination with time travel. The Cthulhu Mythos here is less inscrutable and more overtly malevolent but it works well for a story about women attempting to avoid becoming fodder for their Innsmouth-esque plot to take over the world. Thankfully, all of the implied ick that kidnapping women from across time to breed monster babies is thwarted as well. It's not that kind of book. It's more, "stab the crazy squid cultists in the face."
If this sounds like your sort of thing then definitely check it out. I love David Hambling's occult mysteries more but this was a quirky and fun book despite its sometimes dark subject matter as well as offbeat concept. It's a great combination of fantasy, science fiction, Cthulhu Mythos, and more. I think if you like any of that, you'll probably like this book.