Anyone who has enjoyed Henry Porter’s excellent series of Paul Samson spy thriller novels will be pleased to hear that he has a new protagonist, Alice “Slim” Parsons, who is every bit as dynamic and charismatic as Samson. She takes central stage in this superbly twist-laden novel, and swiftly establishes herself as a heroine for the ages. There’s plenty of sly wit on display as Parsons, a former deep cover MI5 agent – whom we are introduced to semi-reluctantly saving her mother’s life – is dealing with the aftermath of a close-quarters, near-fatal struggle in a private jet somewhere over the Balkans, in which we learn that she isn’t someone to be messed with.

The age-old trope of a burnt-out spook who has attempted to leave the security services, only to be lured back for one last job that will have a significant personal and professional impact on them, was a cliche even when John le Carré wrote The Spy Who Came in from the Cold in the early 60s, so it is to Porter’s credit that he takes potentially hackneyed material and makes it fresh, fun and gripping. Much of the book’s success lies in its innovation and wit. Slim finds herself working with an association that has a mysterious relationship with the former Bletchley Park code breakers, allowing the author to look at matters of national intelligence past and present with a realistic, though never wholly cynical, gaze.

This is a lengthy book, and some readers may find that the action occasionally drags. Yet the third act, in which Slim confronts nemeses old and new, is especially thrilling stuff, and I defy any reader to reach the bleak but cathartic conclusion and not want to dive into another adventure with the redoubtable heroine. Porter has been compared to Mick Herron and Gerald Seymour, and it’s easy to see why, but The Enigma Girl is the work of a wholly individual and readable talent.

• The Enigma Girl by Henry Porter is published by Quercus (£22). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply