Possibly for the first time in the series, I'm not quite sure what I think of this particular book. It breezes along like a house on fire, so it's inherently enjoyable, but it feels ephemeral, as if the pace hides a lack of substance. In reality, of course, its value is probably somewhere in between those two.

It feels good from the outset, with a characterful Alfred Hitchcock introduction, very likely the best such in a long while. William Arden then throws right into the action, courtesy of a will, the will of Marcus "Dingo" Towne, which is advertised widely in the papers. He was a rich man, you see, and he's promised his fortune to anyone who finds it by solving six riddles. To counter any legal backlash from family, he deliberately leaves a single dollar to each of his relatives. That's a daughter-in-law, a grandson, a nephew and a niece. He even trawls Hitch in as an executor, not an act that makes the director happy.

And so we're off and running before we can even breathe. Cryptic treasure hunts have been a staple of the series since the second adventure, 'The Mystery of the Stuttering Parrot', and it's clear that Arden favoured the approach, having used it in both his previous books, 'The Mystery of the Shrinking House' and 'The Secret of Phantom Lake'. However, this is quite easily the most blatantly he's launched into it, literally plastering it across the front pages. We soon learn that it's a cool million bucks in precious stones, which are easily hidden.

What that means, of course, is that everybody and their dog is on the hunt for Dingo's fortune, not just the Three Investigators and maybe a couple of other sinister parties in the shadows. It also means that the first stop on the quest, namely Dingo's house, is sprawling chaos, with the population of Rocky Beach tearing the place up trying to figure out how to solve the first clue. Fortunately, few of them manage that so the hunt calms down considerably as we move to the second. Unfortunately, that few includes Skinny Norris, the boys' old nemesis, once again right in their faces.

As is pointed out here in dialogue, Skinny "always goes too far", and that means serious danger in this book. He strands the Three Investigators on a houseboat that he's let loose on the water hurling downstream towards a dam. That's the sort of thing that could get the boys killed and I have to point out that, while of course that doesn't happen, Skinny fails to get any substantial comeuppance for doing something so reckless. Sure, the boys win and Skinny loses, but that's a given. Sure, Skinny ends up in an embarrassing situation that the boys get him out of, which is a sort of poetic justice. However, he deserved legal ramifications for this particular action and he gets away with it scot free.

A more serious problem is that almost nobody figures out that first clue, which shouldn't be as hard as it's made out to be. Now, I first read this book as a kid in Essex, which is one county east of London, and my family goes back to the East End pretty quickly on both sides. As we were all fans of language and wordplay too, I likely knew what Cockney rhyming slang was by the time I was standing up on my own without help. Fortunately, Arden deepens his clues so knowing this particular form of language isn't enough, but it's one heck of a start.

I will, of course, happily acknowledge that teenage boys on the west coast of the United States aren't likely to have the advantages I had of location and genealogy, just as I had no clue how to pronounce most of the Spanish words that the Three Investigators had grown up with. That said, America is an incredible melting pot of different cultures and California is undoubtedly a pristine example of that. There were surely plenty of Eastenders in Hollywood when this came out, not least the one on the front cover—Alfred Hitchcock was born in Leytonstone, which is in East London—and I struggle to believe that none of them knew what "apples and pears" were.

But hey, I'll let that slide, I guess. This is a children's mystery, after all. Instead I'll praise Arden for varying those relatives. We're automatically led to distrust them because we're on Dingo's side from the outset, even having not met the man. If he didn't have any time for them, then it would seem that he had good reason. However, Billy Towne is only seven-years-old and it's hard to understand leaving a seven-year-old kid out of your will. His mother Nelly seems nice though she's engaged to a lawyer, Roger Callow, so that means that she's suspect. The niblings, on the other hand, Winifred and Cecil, are clearly bad eggs from the outset and continue to get worse as the film goes on, resorting not just to dubious decisions but clearly illegal activity.

At the end of the day, though, a book like this is always going to live or die by the quality of its riddle. The good news here is that, my disbelief that nobody in California has apparently ever heard of Cockney Rhyming Slang aside, it's a pretty good riddle. In fact, one detail about that slang works well, namely that it's not all traditional. Those of who have heard of it know about "apples and pears" being stairs, for instance, but Arden underlines that the people who use it often conjure up their own rhymes. It's an ever-evolving slang, with plenty of newer examples that weren't available to Arden in 1974. Now you can pop down the pup for a couple of Britneys or update your anti-virus software to ensure you don't catch a Billy Ray. Thus Dingo's originals are appropriate and neatly tricky.

I also particularly appreciated how, even when a clue seemed particularly easy, it wasn't. There are quite a few that tie specifically to Dingo's life, so that the traditional investigation method of simply talking to people who knew him has a habit of connecting dots. However, even here, a few have catches. There's one in particular that I don't want to spoil that relies both on an easy answer obtained from talking to one of Dingo's friends and a particular insight into his nature. If you only get the first half of that, you'll understand how to solve the clue but you'll also get it wrong. You have to have the second half of it too.

And all of that means that this book had a lot of potential to go horribly wrong but resisted the urge at almost every point. No, it's not another 'Stuttering Parrot', but it's a decent puzzle and it's a non-stop action ride, with a few neat little touches to elevate it. My favourite such is Billy's part in proceedings. Being seven-years-old, he's easy to dismiss, especially when he shows up at the Jones Salvage Yard thinking he's a detective, and the Three Investigators dismiss him, even though they're rather used to people unfairly dismissing them for similar reasons. Over time, it becomes clear that Billy isn't stupid and, while he certainly hindered the investigation early in ways that a seven-year-old might, he helps it later on, too, and the boys both accept and benefit from that help.

Arden only got one book at this point in the relay race he was now running with M. V. Carey, so she'll be back next month for a couple, starting with 'The Mystery of the Invisible Dog'. ~~ Hal C F Astell

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