Helen Moss Books in Order

The circus brings color and excitement to Castle Key, but trouble is traveling with it. Beneath the glitter and tricks lies a dangerous mystery, and Scott, Jack, Emily, and Drift soon find themselves under the big top with real stakes.

A stormy game in the lighthouse leads to a battered treasure map and the promise of hidden gold. The clues are tricky, the competition is dangerous, and Scott, Jack, and Emily are not the only ones on the trail.

A film shoot at the manor house should be exciting enough, but then the movie's star disappears. Scott, Jack, and Emily must sort through gossip, old legends, and midnight shadows to work out what really happened.

After thieves raid a neighbor's house, the children are puzzled when the victim seems to want the case left alone. Their search uncovers links to an older crime and a mystery worth far more than the burglars first took.

A run of bizarre crimes points to the unlikeliest suspect of all, a skeleton. Scott, Jack, Emily, and Drift have to untangle the strange pattern before the culprit slips away again.

Scott and Jack expect a dull summer with their great-aunt, then they meet Emily and Drift and stumble into a real mystery. When treasures are stolen from the castle, the strange caves nearby may hold the key.

Bones found in the quarry look like evidence of murder at first, but the truth may be far older. As rival scientists argue over dinosaurs and dragons, the friends dig for answers of their own.

Scott, Jack, and Emily pull a man from the sea, only to learn he cannot remember who he is or why he was there. The deeper they dig, the more it looks like the waves were meant to finish the job.

A mysterious new resident arrives in Castle Key with bulletproof windows and an agent apparently watching his every move. Scott, Jack, Emily, and Drift suspect espionage, but the truth behind the stranger is even harder to pin down.

A dive to an old smugglers' wreck reveals an artefact linked to hidden treasure, then the clue vanishes before anyone can recover it. Scott, Jack, Emily, and Drift are soon chasing thieves, secrets, and long-buried loot.

A top secret prototype car vanishes during a test run, and Scott, Jack, and Emily are suddenly in the middle of a high-tech mystery. With Drift helping, they have to track the missing vehicle and the people who took it.

A young prince disappears during a school camping trip on Castle Key, and Scott, Jack, Emily, and Drift jump into the search. The case turns into a tense race to find the kidnappers before their hostage is moved.

Strange lights, eerie noises, and shadowy figures on the moor set the friends guessing. Whether the answer is smugglers, aliens, or something else entirely, Scott, Jack, Emily, and Drift know Castle Key is hiding another mystery.

When Boomerang the cat uncovers a hidden room in Stone Cottage, the friends find a huge chest and the trail of an old secret. Someone else wants the lost relic too, which turns a treasure hunt into a dangerous chase.

Ryan expects a trip to Egypt with his journalist mother, not a 3,000-year-old murder mystery. Teaming up with Cleo, he follows codes, treasure clues, and a dangerous cult in the Valley of the Kings.

In China, Ryan and Cleo are drawn into a new mystery linked to an archaeological site and a family secret. Ancient poisons, terracotta warriors, and old legends make this a tense step up from an ordinary school holiday.

Sam thinks he has seen the Green Lady in Stirling Castle, but Meena is sure there must be a real explanation. Their search leads to a hidden room, a stolen sword, and a mystery that feels close enough to touch.

Ben hears a strange cry in the storm and finds a whale stranded on the beach. He and Izzy rush to help, but the adult who appears to rescue it may not be as trustworthy as he seems.

Ryan and Cleo head to Mexico for an archaeological dig at the ancient Maya city of Calakmul. Old legends, modern danger, and buried secrets make this another high-stakes puzzle in the series.

Turned into puppies and hurled back to 1925 Alaska, the Time Dogs meet Balto at the height of a deadly crisis. To get home, they must help with a desperate medicine run through snow and danger.

The Time Dogs land on the Missouri River in 1805 and join Seaman, the dog who traveled with Lewis and Clark. Their latest trip mixes wilderness adventure, history, and plenty of narrow escapes.

The Time Dogs tumble into another journey through the past, where the mystery of Anubis and a golden collar pulls them into trouble. It keeps the series mix of fast action, teamwork, and history seen through canine eyes.

The Time Dogs are swept back to the Swiss Alps in 1800, where they meet the famous rescue dog Barry. Together they face snow, storms, and steep mountain danger in a mission to save a trapped boy.

This standalone adventure retells the 1924 to 1925 serum run to Nome through the eyes of sled dogs and the people around them. Balto and Togo lead a desperate race to carry lifesaving medicine through brutal winter conditions.