Behind Closed Doors (Level 10-30)

I did this today, and it was not bugged, for those who are worried about that.

As it states, this quest chain starts by having [item=38567] drop from [npc=4656]. However, there are some quests you have to do before it will drop.

Assuming someone has not done any of the Desolace quests, this is what you need to do to unlock this quest chain:

[npc=36060] in Karnum's Glade, Desolace (58.2, 50.0)
A Time to Reap
Pulling Weeds
Taking Part

[npc=36052] in Karnum's Glade
An Introduction Is In Order (you must turn this in to Khan Leh'Prah before you can pick up his second one)
Cenarion Property Since the objectives are next to each other, you might as well do this and Khan Leh'Prah's follow up quest Breakout! at the same time.

[npc=36056] Next to Garren Darkwind in Karnum's Glade
Breakout!
Delicate Negotiations You will turn this in to [npc=36163]

[npc=36163] Magram Territory (71.6, 45.6), he shows up after you complete the objective for Delicate Negotiations
Will Work For Food
My Word is My Bond

[npc=36056] in Karnum's Glade
Three Princes This will be turned in to [npc=36185]

[npc=36185] He is inside the cave in the southern area of the Gelkis Village (40.4, 95.6)
Not So Fast! Valley of Spears (32, 60.4)
Once you have this quest in your log [npc=4656] will drop [item=38567] which starts Behind Closed Doors.

Edit:
If you already completed the quest chain before this reputation change, then talk to [npc=36034] in Karnum's Glade, and he should grant you the reputation

For those here after Neryssa's post to get both Gelkis and Magram reputation to Exalted in 1 go during BFA Patch 8.01, here are some of my experiences:

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• I ran Neryssa's scripts (i.e. Behind Closed Doors: /script print(IsQuestFlaggedCompleted(14330)) ) and found I hadn't completed any of the 4 final quests on the way to completing Death to Agogridon.
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  • I followed sephyre's comments for Maraudine Prisoner Manifest, and searched for any of the quests in the quest chain starting with A Time to Reap, but couldn't find any of the quests.
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    • I decided to see if I could run the script Neryssa gave, but with the quest ID's found in the URL on Wowhead - i.e. for A Time to Reap this quest has an ID of 14305 seen in the Wowhead URL - something I never knew) I could track each quest to see what I had finished. Lo and behold I had finished the quest chain up to Not So Fast, probably in 2011 when doing Loremaster.
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      • I took a pot shot and went over to Maraudon where Maraudine Prisoner Manifest drops, and the manifesto dropped on the first kill of a Maraudine Mauler!
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        • I finished up the last 4 quests killing Agogridon, handed in the quest Death to Agogridon and immediately dinged Exalted for both Gelkis and Magram reps! Happy days!
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        Good luck peep! Lets hope blizzard doesn't recall this rep ;)

If you're unable to remember what or how many of these Desolace quests you may have done over times gone by, rather than going through each step outlined in other posts here, try starting off by talking to Karnum Marshweaver (57.5, 47.7) in Karnum's Glade. For me, simply right-clicking this NPC immediately put the Margram Clan and the Gelkis Clan factions to a full Exalted standing -- very nice!