The Missing Merchant

Kun-lai Side Story Quest Tree From Whiterock

   S)Temple of the White Tiger{H}(Multiple zones)
   +)A Celestial Experience   {H}
   a)A Witness to History     {H}
   /                           |
The Shrine of Seven Stars(A)* The Shrine of Two Moons(H)*

The Ordo Warbringer{A2,H1,H2}*   +)The Kun-Lai Kicker([zone=6426])
 |
S)Muskpaw Ranch{H}
+)The Missing Muskpaw            +)Fresh Needle Scent
 |           \
b)Yakity Yak b)At the Yak Wash   +)The Late Mrs. Muskpaw
 |           /                   b)The Fearmaster
c)Back in Yak

The Ordo Warbringer{A2,H1,H2}* Barrels of Fun{H}* Pandaren Prisoners{H}*
                          \          |            /
                          S)The Missing Merchant{H}
         +)Repossession   +)My Son...
                          d)Father and Child Reunion

+)The Waterspeaker's Staff +)Enraged Vengeance +)Free the Dissenters
                         \  |       ┌───────────┘
                         d)The Ritual
                         e)Cleansing the Mere
                         e)The Fall of Shai Hu

Legend:
S means Skippable
+ means Can start anytime, prequests not needed.
(A)/(H) means Alliance/Horde only.
{H} means Quest Have Horde Variant, click {H} for it.
* means another Quest Tree.

You are mistaking this with Beyond the Wall, which is 88. And the reason why you can't see this breadcumb quest is probably becose you already completed it or pickedup/completed it's followup My Son...

Does not appear to be a level 87 quest. He has the silver question mark above his head, which suggests that you need to be level 88 to get it.