Unless that mystery winds up with us finding some wee beastie wearing boots.

[Or someone's love letters, or something that wants them to collect flowers or any of half a dozen other ridiculous things he can think of off the top of his head. But maybe they'll find something more exciting instead - and the thought of that is enough to get him to take a second look at his surroundings to see if there's anything that stands out.]

There's a waterfall around here somewhere if we want to try having a go at listening for it, or we can see where yon path here goes. Unless you've a better idea?