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," and "If At First You Succeed"; this one was written before the 2014 hunt and refers to the 2013 hunt. The tag [NI3], as is usual in the National Puzzlers' League, indicates that an answer is in the 3rd edition of Merriam-Webster's New International Dictionary.
Another year, another heist. Once again, six experts are executing, on behalf of a mysterious client, a fiendishly complex plot to retrieve a coin from a vault. (If you've forgotten who these experts are, go now to Round 0 of the 2013 MIT Mystery Hunt and either solve the six regular puzzles or, if you don't care about spoilers for those puzzles, read the Intercepted Memos. Note that solving this cryptic will give spoilers for the Round 0 puzzles in any event.) This time, the plot has three parts:
Part I: Distraction
Two experts will provide a distraction by impersonating other members of the group. Multiple such impersonations are reflected in 25 of the clues, each of which has a single incorrect letter that must be corrected to another letter before solving. Read the incorrect letters and the corrected letters (each in clue order) to see who will be impersonated and, correspondingly, who will impersonate them. (Both these experts are masters of disguise, but as you will see, one has a slight edge over the other.)
The next two parts are sufficiently dangerous that two plans have been implemented, Plan A and Plan B. Specifically, four of the Across "clues" in this puzzle actually consist of two clues, side by side. When solving under Plan A, take the first clue in each case and completely ignore the second; when solving under Plan B, do the reverse.
Part II: Infiltration
The distraction in Part I is intended to cover for two other experts, who will be traveling to the foreign country where the vault is. Reflecting the movements of these infiltrators, some clues not used in Part I work normally but yield an answer that must be anagrammed before being entered in the grid. Where the first character of the answer ends up as the nth character of the entry (in ambiguous cases, take the least such n), circle the nth character of the clue. Under Plan A, the circled characters will identify the infiltrators; under Plan B, they will say what part of the globe that country is at the extreme western end of.
Part III: Delivery
For each of the remaining clues (all of which also work normally) the answer must be entered unaltered, but with one letter on a grid line. These letters will be used by the remaining two experts before they deliver the coin to the client, in two different ways:
Some letters will appear on the two-line segments between dots in the grid; for each, use a highlighter to highlight that entire two-line segment. When this is done, the highlighted segments will form characters in particular positions relative to each other. To see what these positional relations represent, read the letters on the segments, character by character, top to bottom.
The remaining letters will be on external edges of the grid. The full name (first + last) of each of the two "deliverymen" can be written, one letter per line, alongside one of these edges. Read the letters of the names that are adjacent to the letters on the edges, in alphabetical order by the latter, with gaps in ordering indicating word breaks.
ACROSS
1. Saints drinking singer Don's drinks
5. Couple from Wroclaw gets to sleep with the French fighter
11. Hundred-pound voucher
12. Guy on the Tonight Show before Carson's dad, with a hook
14. Get nosy about source of beef substitute
15. Ben or Bob or I had exploded
16. Talked about strap that can be attached to a nit and fall from the sky
17. Made up a story or German art song
19. Odd characters in play see Ross walks in public areas
20. Cubical items in a casino Diana starts to censure
22. Sard mineral with value $1000 would result in wild celebration
23. Oy, gevalt — a king has flipped over President Coolidge
28. Expert to name particle Penny initially resisted knowing about,
immediately
31. Prefix ayin to the prefix "self-" seen in grid I offered
32. Hardships disheartened lupine beasts
34. Somalian capital consists of half of mogul's gold-covered plate
36. Metal that is on undergarment right inside low-voiced New York
native's French restaurant
37. Scrooge's comment about one-meter raised platform in a synagogue
38. Jon wears gold in half of South America, approximately
(2 wds.)
40. Time near mid-month shows lunar effects
42. Creator of a mosaic that's rotated and ignited again
43. Ouse essentially blocked petroleum coming from the east
45. A quantity of cash engulfing Republican district, at first,
doesn't reassure anybody without loud, prolonged speech
49. Spelunker's résumé, which covers middle of bench well
52. 1 & 2 & 998 & 1 & 3 & 7 form a kind of picture
Agent 86 and Jimi barely saw
54. Forsaken actor Chaney consumes 25% of eats
55. Loves having a sec to name a drug with narcotic properties
56. Loose, loose nun takes gym class [NI3]
57. Fellow is to become daw when exposed to the elements
58. Males cooked dinners, perhaps
59. Scale's third tone is produced by dime smashing bag
60. Nurse in nest with chemist Walther
DOWN
1. Bengali relative put Nelly in pit below deer
2. Torn clothing, ultimately, upset Eastern Plains native
3. Lug and vacuous scholastic, with help, run Amoy
4. Hear what happens when neither side wins the moot points in Siam
5. Cost of wax and ink upset pervert
6. Former Charmed actress McGowan got up
7. A Californian baseball team outside of Roseville occupies houses
8. Ensnares north Greek city? Not quite
9. A pope's excellent ring, sported by actress Tyler (2 wds.)
10. Part of dopey nerd's "peepers," in the language of the pest
13. Aphorism about, say, computer pioneer Lovelace
18. Oz redirected some aimless secondary rockets
21. Together, authored neat routine
24. Long nail of coati is 53" from a Roman
25. Inability to smell an empty omnibus before actress Farrow
26. Tune-writing American singes George, Charlie, Oscar, and Mr. Solo
27. Pierces tedious people
29. Behaved like an adder being carried
30. For example, Shrek, Fiona's beam thus gets overturned
33. Aaron's superior's superior destroyed Lear
35. Vowel sequence written around middles of nut, corn, & bead
39. Something made from tin cans is this!
41. Communist with still, after revolution, becomes merchant
44. Hep Al scribbled the first letter in Hebrew
46. Sow casting out old, bad pig food
47. Sounds from a shopping center are damaging
48. Group of trees policemen mentioned
49. Removed the innermost part of cable for a speaker
50. List of words Victor unveiled for "taxi"
51. Actress Moreno clings to a rope
52. Demi Moore's face, bottom to top, communicated speechlessly
53. Adult stops putting crosses into Chinese river