I love a mystery story as do many children and for those young readers, the Adventures on Trains series written by Sam Sedgman in partnership with M. G. Leonard has been – quite rightly – hugely popular. Exciting and brilliantly written, the books have transported their readers around the world as they have joined the adventures of Hal and his Uncle Nat on their travels which – fortunately for us – have coincided with some quite spectacular crimes.

While cowriter M. G. Leonard is well known for her other books, Sam Sedgman writing fiction alone has, up until now, been an unknown quantity but let me tell you that in this, the start of a new series, he has proved that he too can not just tell a story but can do so in breathtaking fashion in a read that had me gripped – a read crammed full of mystery, action and danger set predominantly within the historic Palace of Westminster, and one that has left me in great need of further adventures for its young hero, Isaac.

Opening on the night before the clocks go back, we meet Isaac climbing the many steps inside the Elizabeth Tower – more commonly known as Big Ben – to watch his horologist father Diggory change the time displayed on the clock’s faces as part of his role as Keeper of the Great Clock. With Isaac’s assistance, Diggory stops the clock and prepares to wind it forward the correct amount to adjust it and they discuss the proposed New Time law, which parliament is soon to debate and of which Diggory is not a fan. When one of the clock’s bells unexpectedly sounds, Diggory goes to investigate but when he fails to return and apparently vanishes into thin air, leaving behind his broken pocket watch, Isaac is left bewildered.

Finding himself temporarily in the care of his godfather – Uncle Sol, the Speaker of the House of Commons – Isaac is taken back to Sol’s apartment within the building and the following morning meets his daughter Hattie who he hasn’t seen for years. After breakfast, Sol takes Isaac home to pick up some belongings and Isaac can’t help but notice that his home has been visited overnight by someone other than himself or Diggory. Hoping his father has left him some sort of clue, Isaac opens Diggory’s safe and retrieves his journal which appears to be written in some sort of code and has a small, black envelope addressed to his father tucked inside.

Examining the journal back at Sol’s apartment, Isaac finds a card with a cryptic message on it tucked inside the envelope and while puzzling on it is stunned by Hattie’s revelation that she believes she witnessed Diggory being kidnapped the previous night. Teaming up to investigate what has happened, the two of them soon find themselves at the heart of a dangerous mystery – one which not only threatens Isaac’s father but the heart of the U.K.s democratic system and even time itself.

Isaac and Hattie are a great pairing. He is fascinated by the mechanisms of the clocks his father tends and has the sort of brain that ‘sees’ how mechanical things work and can calculate confidently and tends to be a follower of rules while Hattie is drawn to investigate her surroundings using her physical abilities to climb things and sneak about on rooftops, and is more than happy to go behind her father’s back to do so. Thrown together, they soon become good friends who are able to rely on one another and who complement each other perfectly.

While the Adventures on Trains series has taken readers around the world, the action here is very much on home ground with much of it happening within a very small area with which most of us are surprisingly unfamiliar. Sure, we’ve seen the House of Commons on TV, and we all recognise the Elizabeth Tower, even though we all misname it, but very few of us have any idea as to what else is hidden away within the building, making it an ideal place to set a mystery. As Isaac is introduced to its secrets by Hattie, who has already used her connection to Sol to investigate thoroughly, we too start to see it as so much more than a tower and a debating chamber as well as learning more about its traditions and the roles of some of its staff.

I thoroughly enjoyed this story. Hugely believable and action-packed from start to finish this will be enormously popular with fans of adventure and mystery in Year 4 upwards and I cannot wait to find out what Isaac gets up to next.

My enormous thanks go to publisher Bloomsbury and to Net Galley for my advance virtual read. The Clockwork Conspiracy publishes 1st February and is definitely one to pre-order.