by Sean Lip, Ludwig Schmidt and Freddie Manners, with help from Mary Fortune and Jonathan Lee
This puzzle looks like a Cambridge MA runaround with some text redacted -- but, fortunately, it is possible to reconstruct most of the route.
The first thing to figure out is where to start. In order to turn right into Green Street at Step 4, then right again into Sidney Street and carry on in the direction of Elm Street, the left turn in Step 3 must be at Blanche or Landsdowne. Blanche Street doesn't give a 'corner building on left' for Step 4, so the left turn must be at Landsdowne. Thus, the street in Step 2 must be Massachusetts Ave, which means that the starting location (given the context of the puzzle) is likely to be somewhere in MIT. As it turns out, ENIGMA VALLEY was actually recruiting the brightest and best from Lobby 7, and sending them into the city to prove their mettle (but you don't need to know the exact starting location in order to solve this puzzle).
The following notes provide more details about the route taken, as well as the information recorded at each step.
|1.||GRIMSON → S|
|2.||Turn right at Mass. Ave.|
|3.||Turn left at Landsdowne (see the introductory notes for why
it can't be Blanche).|
▢ = 6.
⬠ is defined later.
|4.||◯ = 6.|
Record the letter corresponding to (7 - 6) * (7 - 6) → A
STAR MARKET → R
|7.||If you want to follow the bend to the right then you must
turn left into Main St.|
Junction letter → T
JILL (Brown Rhone) → I → A
|8.||To get to Elm as quickly as possible, turn left onto Harvard St. Street → T. This fills in clue 3 as well.|
|9.||Norfolk St → O ('breaking ties' is irrelevant here).|
|10.||Hampshire, Webster and Cambridge are the possibilities here,
but only Webster shares a name with a prominent Secretary
CAROLINE LEROY → L
|11.||You need to turn left here in order to make it to Norfolk in clue 16.|
|13.||Take the first left onto Cambridge St.|
HAVELI → I → E → D
TREMONT STREET → T → S
|14.||Take the first right into Tremont.|
SPICE AND RICE → C
|15.||Take the first left onto Hampshire.|
|16.||Turn right at Norfolk, violating no-entry sign.|
HAMPSHIRE, no traffic lights → H
NORFOLK CT → O
|17.||Holy person's street → Bishop Allen|
Four-way junction → O
|19.||Turn left into Columbia Street, which we visited in Clue 7.|
|20.||In order to turn left later and continue until you're next to a university, you need to turn left into Broadway or Harvard St ('wide' suggests Broadway). The junction before Broadway is with Harvard St, so ☾ = 7.|
|22.||HARVARD UNIVERSITY → S. So the previous letter was S - 7 = L.|
This gives START AT OLD SCHOOLS.
Googling shows that the Old Schools are part of the University of Cambridge. The solver needs to rerun the walkaround starting at the Old Schools in the UK.
|1.||LORD SAINSBURY → S|
|2.||Turn right into Trinity Lane.|
|3.||Turn left into Trinity St.|
▢ = 3
⬠ is defined later.
|4.||◯ = 4.|
Record the letter corresponding to (7 - 3) * (7 - 4) → L.
SAINSBURY'S → U
|7.||Turn left into Emmanuel St. Follow the bend to Parker St.
Junction → T|
JESUS (Christ) → U → I
|8.||To get to Elm St as quickly as possible, turn left onto Emmanuel Rd.|
EMMANUEL ROAD → O (Also used in clue 3.)
|9.||NEW SQUARE → N|
|10.||To get to Prospect Row you must turn right at Eden St. The
prominent Secretary is Anthony Eden.|
CLARISSA EDEN → I
|11.||Turn left at Prospect Row.|
|13.||The first drivable left is into Adam and Eve St. The building
is the Cambridge County Court which you can see from going to
Satellite View in Google Maps and looking at the Street View
pictures of the other end of the building (which faces East Rd).|
CAMBRIDGE COUNTY COURT → T → S
BRANDON PLACE → E → F
|14.||THE TRAM DEPOT → O|
|15.||Take the first left onto East Rd.|
|16.||EAST ROAD, traffic lights → R|
STAFFORDSHIRE STREET → E
|17.||Turn left into St Matthew's St.|
Three-way junction → I
|19.||Turn left onto East Road.|
|20.||In order to get to a university by turning left, it is necessary to turn onto Broad St or Bradmore St to reach Anglia Ruskin University; Broad St fits the 'wide' clue better. The junction before that is with Norfolk Street, so ☾ = 7.|
|22.||ANGLIA RUSKIN UNIVERSITY → N. So the previous letter was N - 7 = G.|
This spells 'SOLUTION IS FOREIGN', so the answer to call in is FOREIGN.