Sherlock Bones and Dr Catson are entangled in an arithmetic adventure. They must follow a teasing trail of addition- and subtraction-themed puzzles. It's up to the reader to solve each sum, all in the hope of foiling Professor Moriratty's evil plan.

This charming activity book is a fill-in book allowing children to test their numeracy skills. Ideal for children aged 7+, this fun-filled addition and subtraction-themed maths puzzle book allows children to test their numeracy skills.