If a customer comes into the bookstore and says, "Do you have that book, Something Thief?" the answer is probably yes. However, if they can't be more specific one has a bit of a problem.
If
ey says, "It's historical fiction", easy. Ey wants
The Book Thief by Marcus Zusak.
If ey says, "It's a sequel", easy--as long as they're sure the whole title is Something Thief or The Something Thief. Ey wants The Time Thief by Linda Buckley-Archer (original British title: The Tar Man; sequel to The Time Travelers aka
Gideon the Cutpurse).
If ey says, "It's the only one out so far", and they're sure, then it's also easy. Ey wants The Magic Thief, by Sarah Prineas. (No Wiki article exists. At all.)
But if ey says, "It's Greek mythology, and there are sequels", and they cannot--truly cannot--remember a single other thing about it down to whether or not there is a "The" at the beginning of the title, then ey may want either
The Lightning Thief by Rick Riordan (sequels: The Sea of Monsters, The Titan's Curse, and The Battle of the Labyrinth, with at least one more book scheduled for release in 2009) or
Fire Thief (the Wiki article title is, I'm pretty sure, erroneous) by Terry Deary (sequels: Flight of the Fire Thief and Fire Thief Fights Back).
I mean, come on. A little originality with titles plzthanx?