- Chapter Books
- Ages 10–13
- Historical Fiction
Mark of the Plague
Book 2 of 6 in The Blackthorn KeyView the full series
The plague is sweeping London and a charming stranger claims a miracle cure - but Christopher smells a fraud. A dark, fast second mystery about charlatans, critical thinking and a treasure hunt through a dying city.
- Best for10–13
- FormatChapter
The vibe
What it’s like.
Style
- Literary
- Conversational
Tone
- Exciting
- Suspenseful
- Dark
- Adventurous
Themes
Experience meters
What’s it about?
The story.
London, 1665, and the Great Plague is killing thousands a day. Now master of Blackthorn's apothecary shop after his own master's murder, fourteen-year-old Christopher Rowe finds a city ruled by fear - and by charlatans peddling false cures to the desperate. When a mysterious stranger arrives promising a genuine plague remedy, and a prophet foretells that Christopher's best friend Tom will die, Christopher must decide who to trust. With Tom, the orphan Sally and his faithful pigeon Bridget, he races to test the cure, unpick a coded trail left by his late master, and expose a conspiracy that could destroy what remains of London. Kevin Sands follows his award-winning debut with a mystery that pits evidence and reason against superstition, spiked with explosions, sword-fights and genuine period horror. The plague's symptoms and the greed it unleashes are not softened, making this a gripping but properly dark adventure for readers ready for it.
Fit check
Right for your child?
Where it lands by age
A 10-13 read that sits, if anything, at the darker end of the series: the Great Plague's symptoms, mob violence and murder are shown honestly. Confident older middle-graders reading independently are the sweet spot; it reads aloud from about 9 with families comfortable with the content, and appeals to adults too.
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- Best fit · 10–13
- Read aloud · 9–12
- Independent · 10–13
Prose load
Moderate
Visual support
None
Reluctant-reader friendly
Workable
Read-aloud quality
Workable
Preview before sharing if a child is sensitive to: violence, death of character, illness or disability, scary imagery.
Bedtime suitability
1 / 5 · Wide awake
Sensitive-child
1 / 5 · Tough fit
Graphic intensity
4 / 5 · Notable
Best for
- Historical mystery
- Codes and puzzles
- Adventure with danger
- Confident readers
Avoid if
- Wants gentle bedtime
- Sensitive to violence
- Sensitive to death
- Sensitive to illness
Particularly good for children who are…
- Interested in science
Why it lands
Why they love it.
Why kids love it
Christopher is running his own shop now, and the stakes are higher: a plague that could kill Tom, a smooth-talking stranger who might be a fraud, and a treasure hunt through streets full of danger. The puzzles are trickier, the explosions bigger, and Bridget the pigeon steals every scene she's in.
- Being a detective
- Trickery and cleverness
- Surviving danger
- Secret skill
Why parents love it
A rare adventure that dramatises critical thinking - Christopher tests claims instead of trusting fear - inside a vividly researched Great Plague. The history is unflinching about disease and the predators it breeds, so it suits older, sturdier readers, but it is genuinely gripping and smart.
- Great writing
- Educational for adult too
- Conversation starter
In the series
The Blackthorn Key.
6 books · open the series →
About the author
Kevin Sands.
If you liked this
Three ways out of this book.
If you liked this, try…
Lateral matches. Same shelf, different texture.
Come into this from…
Easier or preparing reads — perfect lead-ins.
Where to go next…
Escalation reads — a step up in scale, silliness, or stakes.
More like this…
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