Not strictly part of the fic meme, but I might as well throw it in there.
I had not ever thought of writing such a thing! And I’m afraid I can pretty much guarantee I’ll never write it. But if I did write it, they would find their way to the island because someone had been indulging in dinosaur smuggling. There would be fraught stalking chases through the jungle, as both hunter and hunted, as they attempt to follow and avoid being killed by smugglers and velociraptors.
At some point they would escape a near-death situation by using pterodactyls to hang-glide (I doubt it’d work very well, I don’t think they’re really built to carry that much weight). Sherlock would save their lives a couple of times via organic chemistry, and I think at one point he would simply set part of the forest on fire. Well done, Sherlock. John would befriend a triceratops or something and during the climax he would save the day by inducing a dinosaur to ram into a wall, thus knocking it over on the well-armed back guys (because of course Sherlock only brought John’s pistol, even if he did include extra ammo).
It’s a good thing Sherlock had to get clearance from Mycroft, though, because they really do need a ride out of there by the end.