DE-CIPHER THIS MESSAGE

De-cipher the following message using the ROT1 cipher.
Plain text: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Code:        B C D E F G H I J K L M N O P Q R S T U V W X Y Z A

Message: 
" UIFSF ' T UIF TDBSMFU UISFBE PG NVSEFS SVMMJOH UISPVHI UIF DPMPVSMFTT TLFJO PG MJGF, BOE PVS EVUZ JT UP VOSBWFM JU, BOE JTPMBUF JU, BOE FYQPTF FWFSZ JODI PG JU" (29, DOYLE)

ANSWER:
"There's the scarlet thread of murder running through the colourless skein of life, and our duty is to unravel it, and isolate it, and expose every inch of it."