The Arctic Railway Assassin by M. G. Leonard and Sam Sedgman. Illustrated by Elisa Paganelli.

Hal and Uncle Nat are hitting the rails again. This time, their train is Arctic-bound. They are off to see the Northern Lights. On the way to catch their train they visit Uncle Nat’s friend Morti, who has won the Nobel Prize for her work in targeting cancerous cells with sound frequencies. Morti’s ex-husband Björn worked on this theory too, but he took it in a different direction, creating a sound that could kill instead of cure: the Kill Code. Björn hoped to sell the the Kill Code and become rich. Morti handed Björn in and destroyed the Kill Code for good. Or so she thought until her apartment was burgled, and the window to her laboratory was opened. Hal’s mind snaps into mystery mode: is it possible that someone believes the Kill Code still exists?

Then, during their travels, Hal and Uncle Nat realise they are being followed by an assassin. Hal is certain he can outsmart the assassin – except trickery and disguise is afoot and Uncle Nat must confront a person from his past who he would rather not meet. A person he believed to be dead.

There is a short time to solve the mystery, the stakes are high and Hal’s powers of observation will be called to the test like never before. This is real page-turner stuff and perfect for long winter nights when readers want to be lost in the pages of their books.

One of the delights of this series, as fellow fans will know, is that it relies on illustration as much as on writing to tell the story. The interplay between the two is pitched at just the right level for the young audience … who will notice far more than any adult because their powers of observation are sharper! This makes for brilliant conversation, too, if the book is being shared because readers must keep turning back to pages to past pictures to test their theories against Hal’s sketchbook. Illustrator The Arctic Railway Assassin by M. G. Leonard and Sam Sedgman. Illustrated by Elisa Paganelli has once again done a brilliant job of bringing Hal and his travels to life and my particular favourite images in this instalment are those featuring reindeer.

The Adventures On Trains series took middle grade mysteries in a slightly different direction from the stories which had previously been popular in the market and it deserves credit for adding something new to the genre. Prior to Adventures On Trains, there were lots of Detective Societies where every child was totally invested in solving mysteries above all else. While there are great stories about detective societies too, it is lovely to see some choice emerging in the genre. Both the trains series, and M.G. Leonard’s new series following a group of birdwatchers and their mystery-loving friends, add variety and focus on hobbies that deserved some more of the limelight. It is lovely too to see an author understanding how much a hobby or interest can mean to a young person – and respecting the vast banks of knowledge that young people accumulate about their interests.

The sixth book in this series is perfectly-timed for winter and it makes the reader feel as if they too have travelled to the Arctic and solved a mystery. Meanwhile, I’m looking forward to seeing what comes next from this talented crew of creatives.

• The Arctic Railway Assassin by M.G. Leonard & Sam Sedgman is available now from Macmillan Children’s Books (Received in exchange for review)