Note: This is another in my sequence of post-Mystery-Hunt cryptics, which started with "Still There," "Post-Game Predictions," "The Sequel," "Power Lines," "A Lesson in Cryptography," "Yet More Villainy," "Further Escapades," "Time X*X," "Honeymoon in Segas," "If At First You Succeed", "Another One From The Vault", "Next Winter: Wonderland", and "DAB"; this one was written before the 2017 hunt and refers to the 2016 hunt. The tags [NI2] and [NI3], as is usual in the National Puzzlers' League, indicate that an answer is in the 2nd or 3rd edition (respectively) of Merriam-Webster's New International Dictionary.

(5) For this next Extraction job, you're supposed to get important financial info from a certain big shot, but he just says he keeps seeing one thing where there were two. 14 clues reflect this: Each needs one letter added to its start or end before solving, and two instances of that same letter occur elsewhere in the clue separated by a single, different letter. Read the letters added at the start, and then those added at the end (each in clue order) to see two different kinds of single item he is seeing; the corresponding separating letters will say who he is.

(4 & 3) As you may have guessed, the above was just the big shot's dream. Once out of it, you consult an expert, who observes that for 18 other clues, either (4) the answer must be altered before entry by changing a four-letter word (the same in each instance) to a single letter, or (3) the letter string the wordplay yields is incorrect, having a "trigram" (three-letter sequence) in place of a single letter. (One altered (4) entry is a first name.) Call the single letter in either case the "special letter" for the entry; where the special letter is the mth letter from the start and the nth from the end of the entry, circle the mth letter from the start and the nth from the end of the clue. Then:

• The mth letters from the clues will indicate a new "dream ordering" for the clues.
• The special letters from (4), put in dream order, and then augmented at the start and end as per (5), will say what each single item from (5) really represents.
• The trigrams from (3) — some being repeated — can be overlapped (in an order you must deduce) to form an arbitrarily long description of how to wake the big shot up.

(2 & 1) As you may also have guessed, the above was just the expert's dream. Once out of it, you consult an old man, who notes that the 18 entries crossing the (4) and (3) entries at their special letters can thus also be "dream ordered," by the dream order of the entries they cross. In the clue for each, one word must be altered before solving, by changing a two- or one-letter sequence to a "correct" letter; where the altered word is the xth word in the clue, note the number x. Then:

• The correct letters, in dream order, will say what the items from the expert's vision represent.
• Play a single musical note, of any pitch or length. Then play notes represented by the sequences in dream order, where (2) a two-letter sequence represents a note on the xth step of the major scale starting at the original note, whose length is half or (for the 9th and 18th) double that of the original note, and (1) a one-letter sequence represents a note of the same pitch as the note after it, with the same length as the original note. The result will be a tune that might wake up the expert. Also, the next word after the tune will identify the old man.
• The sequences from (4)-crossing entries, in dream order, will spell out something the old man sees. The sequences from (3)-crossing entries will all be directions; for each, move the special letter x spaces in that direction, to see a different example of …

(0) Oh no! In crossing a boundary, you've slipped from the old man's dream into chaotic Limbo! (So each of the remaining 18 answers must be anagrammed before entry; altered entries include a river, a country, a Latin phrase, and a hyphenated term.) For each letter beyond the bounds of the grid, move it ahead x in the alphabet if you moved it vertically, and back x if you moved it horizontally (leaving it unchanged if you moved it diagonally). Then reading (a) the leftmost 14 special letters left to right and (b) the topmost 14 special letters top to bottom will give you an expanded name for an organization with the necessary expertise to help you; read the extra four from each of (a) and (b) to see how they will use what they have to navigate the random chaos out here.

ACROSS

1. ¡Ole!s of wood cutters primarily accompanying bar's inept parasites
9. Diddley meets, in Finance, the stringy animal-catcher
12. Outspoken nobleman means to hold up a bridge
13. Nit replacing Troy with Uhura ultimately upset people in Japan
14. Ex-Beatle Sutcliffe grabs bisected pectoral devices that help in seeing
16. Averse wacko chases 501 fast people?
18. Attach/append a number to a real old automotive mode
19. An official rebuke Peru's less quiet trio of necromancers directed towards poet
20. Ice dweller's one nabbing snake Thomas heartlessly displaces [NI3]
21. Rodent and arachnid beheaded flightless bird
23. A character selling stuff that is spicy and must hurt dear Ira's belly [NI3]
26. Applause and laughter at new defendant's nos
28. M-type sun, say, initially resembles Edward's gob (2 wds.)
31. Bless Master Simpson's skills
32. Film performer Julia Roberts's face strikes gold, at length
33. In Quebec, milk 25% of your flock
34. Chicago author's muonic emitter
37. Shut up about nickel, dude (2 wds.)
38. Gran almost somersaults in (say) an SF film with Kurt Russell
39. You and I, at 1, switch to solid foods
40. What might carry a Bostonian or Achaean's letter, if there's no cod (2 wds.)
42. "Almighty" maker of the giant boas in a Steve Carrell movie part of a church flipped over
43. Lacking legitimacy enough for an Italian with real drive
45. Weirdly coos "minus moss" in vid, exhibiting a speech sound with no oral friction [NI3]
48. Directed at one German's wheel adjustments (hyph.)
49. Kit for a ballerina eating chiefly semi-sliced cereal for breakfast
52. The señores of Algeria, in part, turned ye green and citrus-scented
56. Tally produced by Virgil, Dotty, Ian, & Dee
57. Nine embedded in austere, crystalline devices that send sonic waves out
58. Tunes gathering equipment inside South Dakota's rotating decahedral randomizers (hyph.)
59. Ourself, in Paris (a place 970 miles from Murray, KY) with actress Hatcher
60. A gym's mirrors
61. Term for "organization" that has been made much shorter (like "tie") (abbr.)
62. Finish with sheepish grousing of luminaries with helpful vocabularies

DOWN

1. Reportedly jar man-eating Nile-dweller with armored ski
2. Terrible date precedes anger
3. Adds bright points to street surrounded by ursines [NI2]
4. Somber group that (in part) gives Knossos a try, or Nineveh
5. Once again cut grass with that thing
6. One who digs unimportant sounds
7. Vessels made from copper, by the way
8. Is waiting to write "Dee Snider" out front
9. Animal doesn't accept a defeat
10. Nicholas, e.g., firing warriors and those who make clothing stiff [NI3]
11. British plane-movers recycled penniless Drew's rad dis
14. Dicot lacking cobalt sickened Rudy? Tough
15. Adam's third son despises climes without Ace
17. Because malapropos tint covers most of smuggler Sol (2 wds.)
22. Ornament that fits below the jaw-tweaking offshore roughneck carping at the pro
24. Them, in Mission: Impossible When Compared With Supporting Earth
25. One country, Georgia, making a sinner of upright, feeble Greek character
27. Very odd part of ax, lei, etc. on Justice Samuel
28. Gar, when lifted, reveals musical pattern like Mohanam
29. Misquoting — centrally — Harvard's rival from the south, with brio
30. CEO mishandled batik, denuded a ria, and flooded zoos?
35. Chic, vacuous dilettanti beset it with blue material
36. Regard intensely tart "E" as awful (2 wds.)
38. Boise is experienced by short prima donna that keeps old ducks
41. Loopily ran Steve's lights at about 6 PM
43. Again take in dress unveiled at ball
44. Officer at Little Bighorn had mentioned a pudding-like confection
46. One radical lady bitten by Gordon Sumner's passerine bird
47. Buck's sisters finally get Art performing
50. Put just enough money in to cover half of seething, smothering Utah
51. Re: Ale — principally Guinness and such (2 wds.)
53. Clear vase on the radio
54. Oman's to be west and east (and east and west) of evergreens
55. Eats insufficiently wooden rods adorning third of jars