The Other DaVinci Code

 It was a small, long, plain wooden box,
 containing eight blocks,
 each intricately engraved
 with a single letter.

The letters had to be arranged in their
box according to the following rules:

1. H was two places to the left of U.
2. T was three places to the left of M.
3. A was two places to the right of U.
4. X was two places to the right of O.

However, the cryptic instructions stated
that exactly one relationship was a lie.

Of course, Leonardo soon realized there were
 many possible solutions. Then,
 just as he was recovering the soap from between
 his toes in the water he
 saw his arrangement, which made no particular
 word in the box, with the
 M four places from H and three to the right
 of the W. What was Leonardo's

OHWXUTMA is the correct answer!

HWTUOMAX is the correct answer!