We have an important mission for you

You are an agent working for your country's intelligence services. Recently you received a tip off about a meeting that will be held by a Secret Society who poses a threat.

Sure enough, a few days later you intercepted the following letter and detained one of the members:

To the member this may concern,

Sorry but safety is our priority to start. Don’t worry though and now you’ve got this your other contact will meet you somewhere out there that’s suitable to begin. Remember that the meeting is cancelled and now all that’s left can not be mentioned, even one word. Orally, we all want this to end here and all agree this shouldn’t happen again once we’re third. What comes next naturally is to join another team from here and benefit from each. Thanks for your hand in this and we’ll see how things go, seek where we now are from. Suitably, there are fellow members near, all of them somewhere close, reach them by letter. Agents are everywhere out there and maybe they will look around for you third. Leaving with all that, otherwise good job, meet us soon, carefully take what’s needed to take.

A Secret Society

This doesn't make sense to you as it appears that the meeting is cancelled...

A few items were confiscated from the detainee:

First there was bus timetable, information booklet and map:

The bus company itself isn't mentioned which puzzles you...

Next there was a phonebook with some weird names... :

And finally there was a travel log and a diary:

Your team has helpfully uploaded all text into an easily accessible google doc for further analysis.

The items have left you stumped...

Can you find the meeting details... before it's too late?

• There are a lot of different parts to this, so I recommend partial answers... – Beastly Gerbil Nov 14 '17 at 7:19
• All solved, see commuity wiki for complete wrap-up (and for extra bits which were missed) – Beastly Gerbil Nov 14 '17 at 16:59

Just to add further insight to the letter:

As mentioned by @Sid, the italicized letters in the body spell out FIRST LETTERS. Taking the first letters of each sentence in the letter then give "SDROWTSAL", or "LAST WORDS" in reverse. Taking the last word of each sentence then gives us "Start/ Begin/ Word/ Third/ Each/ From/ Letter/ Third/ Take", which can be reversed yet again to give "TAKE THIRD LETTER FROM EACH THIRD WORD, BEGIN START". Whew!

Following those instructions:

We get the message "FIND THE TIME DATE LOCATION AND WE WILL MEET YOU THERE" (credit: @Fabian) This tells us what we need to uncover. And yeah, I cannot even begin to imagine how OP managed to embed that message in the letter along with everything else.

Bus Timetable/ Route map:

The coloured routes corresponds with the bus company introductory text. Follow each coloured route from start to end, in the ROYGBIV sequence, and you will get "FIRST RED DESTINATION SECOND ORANGE ETC". Take the first letter from the red destination and so on to get "DEC NINE". This should be the date of the meeting.

The first letters of each departing point of the bus routes do spell out "TAKE BUS" as pointed out by @Sid. The last letters of the same points reveal the full message: "TAKE BUS NOS AWAY".

Phone Book:

The numbers under the word VERTICAL tell you which letter to take from each person's name. "5" appears as the 3rd from last digit in Bert Remme's phone number, so we take "M", and so on. This tells us "MIDNIGHT". This is probably the meeting time.

• This letter from every third word is: "mnfindthetimedateandlocationandwewillmeetyouthere"->"Find the date and location and we will meet you there." – Fabian Röling Nov 14 '17 at 10:55
• In answer to how I managed to embed that in the message with everything else - a lot of angry screaming at my computer until it worked :P – Beastly Gerbil Nov 14 '17 at 13:42

Booklet and map:

Overlaying both images revealed several new words for us Red: FIRST
Orange : REDDE
Yellow: STINA
Green: TIONS
Blue: ECOND
Purple: ORANG
Violet: EETC

This says FIRST RED DESTINATION SECOND ORANGE ETC. Based on this hint we can take the first, second, third and so on letters of the destinations in the bus timetable to get DECNINE - December 9th?

Phone numbers:

There are 8 names, each with 9 letters, and corresponds to a 9-digit number. The hint (VERTICAL) comes with an 8-digit number. Each of these number corresponds to each phone number (in order from top to bottom).

We can take note of where the hint's number occur in the phone number (i.e. for the first number, 5 appears at 628914537, third from last). Taking the letter at that position in each name, we get MIDNIGHT

This isn't a complete answer. Just some observations so if anyone gets an idea, they wouldn't have to do too much digging.

LETTER:

The italics spell out "FIRST LETTERS". However, taking the first letters in the letter don't give anything great or meaningful.

TIME TABLE:

The first letters and last letters of Arrival stations give "TAKE BUS NOS AWAY" which doesn't seem particularly helpful. The last letters of the Destination Stations give "NICE TRY". Humph.(Well played, BG)

PHONEBOOK:

@Xenocacia has shown but I did figure it out independently. The point being taking the letter corresponding to the unique number given in the numbers above VERTICAL giving us "MIDNIGHT".

DIARY:

Some of the letters are bolded. However, it's not quite clear which are bolded and which are capitalized. But, here's where the ever helpful google doc comes to the rescue and observing the diary page in the doc leads to the phrase, "COMPASS IS INDICATOR" (I had written IN DICATOR because I am a stupid idiot.) The first letters of the page spell out "PENULTIMATE LETTERS". Taking the penultimate letters from each line gives us "WHERE TWO LINES CROSS". (The answer to that is intersection point. But, this is probably an instruction and not a question)

TRAVEL LOG:

Seeing the first letters of the places, we see, PARA/WORD/LETTER. This seems helpful and probably means we have to do something with words, paragraphs and letters. Now, The Dates are important. Why? Because they are NOT months/days/years! They are Para/Word/letter!(@M Oehm gave a subtle spoiler in The Sphinx Lair.) Using that on the Diary Page, we get, DICTOOIA IABERLOO - This doesn't make sense until you see if we can get V instead of D, W instead of I and T instead of B, there is a legitimate place coming out of it.I am willing to think this is an error by OP and would be rectified soon. Anyway if we do that, we are probably going to get VICTORIA WATERLOO and then, we have to get two lines to cross. I am guessing these are rail lines or something like that but I am not completely sure.

• INDICATOR not IN DICATOR :P – Beastly Gerbil Nov 14 '17 at 7:47
• Some other notes, maybe add the first letters from the letter for others or maybe you’ll realise something. And TAKE BUS is only half of what is hidden in the arrival stations – Beastly Gerbil Nov 14 '17 at 7:48
• I first thought it would be Victoria and Waterloo, too -- the'ye railway stations in London. But the OP told me in chat that the second starts with B, so it's probably Bakerloo. Victoria and Bakerloo are lines of the London Underground. They even cross. :) – M Oehm Nov 14 '17 at 15:59
• You can probably get the location now with the correct dates and the compass now – Beastly Gerbil Nov 14 '17 at 16:24
• Hint... (@MOehm if you want to finish this off too) – Beastly Gerbil Nov 14 '17 at 16:47

Complete Answer by OP

The puzzle was solved by Sid, MOehm, Gwendalen, VotBear and Xenonacacia. Please upvote their answers too.

The Letter

The letter contains italics spelling out first letters. The first letters are SDROW TSAL, which is LAST WORDS backwards.

Taking the last words, starting at the bottom, gives the message TAKE THIRD LETTER FROM EACH THIRD WORD BEGIN START. Taking the third letter from each third word, starting at the top gives this message:

FIND THE TIME DATE AND LOCATION AND WE WILL MEET YOU THERE

It seems as if the meeting isn't cancelled after all...

Bus information

The bus numbers say VIEW MAP in A1Z26. The last letters of the destinations also say GOOD TRY.

Taking the first letters, then the last letters of the 'departing from' column gives TAKE BUS NOS AWAY.

If we take the bus numbers away from the times we get OVERLAY in A1Z26 again.

So overlaying the two grids:

Taking the letters in order of the rainbow gives the message FIRST RED DESTINATION SECOND ORANGE ETC

Taking the first letter of the red destination, the second of the orange, third of yellow etc. gives the date:

DEC NINE

The phonebook

Each name is 9 letters and each number is 9 numbers. Assigning a letter to each number 1-9 and rearranging we get a message (This was originally missed):

REMEMBER THE TYPICAL WAY WE HIDE OUR INFORMATION AND USE IT AGAIN HERE TO GET THE TIMING

At the bottom, it says VERTICAL with some more numbers. Assigning each number to a column and taking that letter gives

MIDNIGHT

The Travelling items

The first letters of the diary say PENULTIMATE LETTERS. Taking the penultimate letters gives WHERE TWO LINES CROSS. The bold letters also say COMPASS IS INDICATOR

The first letters in the locations of the travel log also say something: PARA/WORD/LETTER. This is a reference to the dates. Taking the day as the paragraph number, the month as the word number and the year as the letter number gives:

VICTORIA BAKERLOO

These are two rail lines on the London underground. Looking at the map, the two lines cross over, as indicated by the compass, at

OXFORD CIRCUS

The meeting is being held

DECEMBER THE NINTH, MIDNIGHT, OXFORD CIRCUS RAILWAY STATION

• Can't imagine how much effort it must have taken to create that phone book clue, and yet we (puzzlers) simply skipped past it to get the word MIDNIGHT. Man. Sorry? :/ – Xenocacia Nov 15 '17 at 6:08
• Agreed with @Xenocacia. We skipped so many steps that must have been so painstakingly difficult to make, apologies for that :P Seriously though, seeing the proper solution made this puzzle even more amazing than it already is. Amazing work! – votbear Nov 15 '17 at 6:12
• @VotBear and Xenocacia thanks :) don’t worry about the slipped clues, you got most of them anyway – Beastly Gerbil Nov 15 '17 at 7:01

Small addition to what've been previously said :

(THIS IS FALSE) I think that "TAKE BUS NOS AWAY" means "TAKE BUS NO 5 AWAY" so the meeting take place the 9 of december at midnight (see the other comments) at KLAMATH FALLS ! (Because he must take it AWAY so the depart place is the meeting place)

And with the answers from Sid & VotBear, I think that

(THIS IS FALSE) If we take the letters at the intersection of two bus lines it will give us something, but I don't manage to have something ...

And...

(CORRECT IDEA) About the travel log, First letters says PARA/WORD/LETTER and I think we must take the "dates" from the time log, I mean for example :for the first one we must take the Para 9, word 6, letter 1 of the Diary.

AFTER the comment of Beastly Gerbil, I added that part :

With the travel log and the diary I've found "dict o oiai a berloo" but maybe that's not right... and I don't find what that means ^^'

Another ideas :

The bus numbers says "VIEW MAP" (I realized it thanks to Sid's comment)

LAST UPDATE :

So we find BAKERLOO and VICTORIA, and in the london railway they cross at Oxford Circus so the meeting is the 9 of decembre at midnight on oxford circus.

• The last section is correct, the rest I’m afraid isn’t – Beastly Gerbil Nov 14 '17 at 14:31
• Okay, thanks, I'll continue to try then ^^ (and, wow, it's a very good puzzle, i'm amazed of all the work you've done here ^^) – Gwendalen Nov 14 '17 at 14:46
• The bus nos. related to that part of the puzzle. I am fairly sure each part is solvable on its own.(Also, in case you are curious, A-1 Z-26 for the numbers and take-away almost always means subtraction. You will get what we had to do there...) – Sid Nov 14 '17 at 14:57
• Ohh, okay thanks ^^ I see now ^^ (Didn't know for take-away, english's not my mother tongue) Thank you ! – Gwendalen Nov 14 '17 at 15:05
• I’m afraid I think the last part has several errors I can check soon – Beastly Gerbil Nov 14 '17 at 15:38