How a book works
You are handed a county's register of births and a bundle of memoranda from a firm of solicitors. Each memorandum rules somebody out. Strike out everybody it excludes, work through them all, and exactly one entry is left standing. That person is the heir, and finding them is entirely your work.
The register
The bulk of the book is a register: thousands of birth entries from a fictional county, each with a register number, a name, a parish and a year, set in three columns of small type. The short book holds 9,540 entries across 53 pages of register and eight parishes. The long book holds around 48,000, and runs to a couple of hundred pages.
It is built to be marked. The entries are set at a size you can strike a line through with a pen without losing the ones on either side, and the page you are working is the page you keep returning to.
The memoranda
Bound in with the register is correspondence from the firm handling the estate. Each memorandum states one fact about the heir, and every fact is a filter you can apply to a name and a number by looking at them:
- The heir's surname contains at least one letter E.
- The heir's given name is six letters long or longer.
- The heir's register number contains no digit 7.
- The heir was born in 1853 or later.
Everything you need is on the page in front of you: no outside knowledge, no arithmetic beyond counting, no leap of insight to wait for. What it asks of you is attention, held for a long time, which is the pleasure of the thing. A short book has sixteen memoranda; the long book has twelve, which sounds easier and is not, because each one is cast over five times as many people.
What is guaranteed
This is what makes a Find the Heir book different from a puzzle in a magazine. Before a book is printed, three things are proved about it, and a book that fails any of them is never issued:
- Exactly one entry survives every memorandum. Not "we believe one". Every entry in the register is tested against every memorandum, and the count of survivors is one.
- Every memorandum earns its place. Remove any one of them and more than one person survives, so nothing in the book is padding and nothing you work through is wasted. No memorandum is redundant.
- The work cannot be short-circuited. No small handful of memoranda collapses the register on its own, so there is no shortcut to find and the hours you put in are the hours that solve it.
A puzzle that turns out to have two answers, or none, has wasted an evening that cannot be given back. That is why this is proved before the ink rather than after the complaint.
How you know you are right
The book ends with a verification page. Take the register number of the person you believe you have found, put it through a short piece of arithmetic anybody can do by hand, and compare the three-digit figure against the printed table. A match confirms it. Solving on screen, the site does the same job the moment one entry is left standing, and tells you there and then.
So you get certainty at the end without ever being handed the answer. That is deliberate, and it is what you are buying: there is no solution page, no appendix, no key upside down at the back, and this site will not tell you either. An answer key is the one thing that can spoil a puzzle you have paid for, and it only has to be glanced at once. Verification gives you the finish without the temptation, and a "no" tells you only that this is not the one. It never names anybody and it cannot be read backwards.
How long an evening is it
About four hours for the short book, in one or two sittings, which is a full evening of the good kind. The long book is a much longer sitting, and is better thought of as a project you come back to than an evening you finish.
Treat that four hours as a rough figure rather than a promise. It comes from one reader timing one book, and readers vary more than books do. Somebody who strikes carefully and rechecks will take longer than somebody who trusts their first pass.
Paper, screen, or both
Every book is a PDF you can print and mark with a pen. You can also solve it in a browser here, where striking an entry is a click, the memoranda sit in a drawer beside the register, and your work is saved as you go. The two are the same book with the same register numbers, so you can start on paper and finish on a screen, or the other way round, and pick up exactly where you left off.
Every book is yours alone
Every book has its own register, its own memoranda and its own heir. When you buy one, it is taken out of stock and put in your account for good, and it is never sold to anyone else. Because nobody else has been issued that book, the solution to it exists nowhere except in the work you do, so the puzzle stays a puzzle for as long as it takes you. That is a promise a magazine cannot make, because a magazine prints one puzzle for everybody and the answer is in circulation by the weekend.