MI6 has discovered a recently activated Soviet Sleeper Cell operating in London, they've given the task to you to determine where, when, and how they will strike.
You come across the location of their last known meeting, the trail is several hours cold, but they've left a chessboard out looking like this.
A book is open to a historical game: Spassky v. Bronstein, Leningrad, 1960 complete with movelist and analysis. (For your convenience, the move list follows):
1.e4 e5
2.f4 exf4
3.Nf3 d5
4.exd5 Bd6
5.Nc3 Ne7
6.d4 0-0
7.Bd3 Nd7
8.0-0 h6
9.Ne4 Nxd5
10.c4 Ne3
11.Bxe3 fxe3
12.c5 Be7
13.Bc2 Re8
14.Qd3 e2
15.Nd6 Nf8
16.Nxf7 exf1Q+
17.Rxf1 Bf5
18.Qxf5 Qd7
19.Qf4 Bf6
20.N3e5 Qe7
21.Bb3 Bxe5
22.Nxe5+ Kh7
23.Qe4+ Kh8 1-0
You can tell it's the game for which the end position is on the board.
In the trash you find a crumpled index card, one side covered with mysterious writing.
S1R23R23S9s2p22 S9R23 S10S1S18P20
s19r6P17P20S7P5S3R23R8P15 s2p13S6S2S6p5R23
s13P22R23S5p13S1R18
Hint:
The method of encyphering is one->many, in database terms, however each symbol in the ciphertext decodes to exactly one symbol in plaintext, depending on the key used.
After several hours of investigation, you receive a call from your superiors.
Be careful, we have reason to believe this group has acquired a dangerous spore-based biological agent they may use in this attack.