The Dwarven Ledgers

Queen Ysolde the Old has appointed you Royal Cartographer of Aldermere and sent you east into the Ironvault, the dwarven halls under Anvilback Peak, where the gold has been going missing by exactly the amount of the ledgers’ errors — which is to say, nobody knows. Dagmar Deepdelve, Reckoner-General, ink-stained and sharp, will let you audit her mountain on her terms: every run of cells has its tally carved above it, no digit is counted twice in a run, and a shaft that does not add up has been robbed.

Inside this book

• 100 cross-sum logic puzzles in ten levels of the mine, from 6 × 6 ledgers in the Counting House to 12 × 12 ledgers at the Root of the Mountain
• Four difficulty grades, Apprentice to Reckoner, rising as the mine goes deeper
• Every puzzle has exactly one solution and can be solved by logic alone, without guessing — each one was checked by computer
• Clear rules, a step-by-step worked example, six solving techniques and a table of fixed tallies
• A story told in the cartographer’s survey journal, with a twist revealed only after the solutions
• Rich black-and-white ink illustrations: a cutaway of the Ironvault, a full-page picture for every level, a bestiary page, and a small horned owl hiding in seven pictures
• Full solutions and big cells with room to write

How it works. Fill every white cell with a digit from 1 to 9. The number above the diagonal in a dark cell is the sum of the run to its right; the number below it is the sum of the run beneath. No digit repeats within a run. That is all — and it will keep you underground for a long time.

For adults who love number logic, fantasy and a well-told story. Book 4 of the Owlbrook Legends series; every book stands alone.