Stage 1 is located where it is reported that the Braidfute family's townhouse was located. Marion Braidfute is believed to have been married to William Wallace, marrying in St Kentigern's Church in the town.
The Scotsman William Wallace led an uprising against the English and killed the Sheriff of Lanark, William Heselrig. The attack was not an isolated incident, but rather saw Wallace joining in with uprisings taking place across Scotland.
The best account comes from the Scalacronica by Thomas Grey, whose father, also called Thomas Grey, was present. A fracas broke out at a court being held by Heselrig, but Wallace was able to escape with help from an individual named Innes who may have been his wife. He then came back with some supporters and attacked Heselrig and his men, killed Heselrig, nearly killed Thomas Grey senior, and set fire to some houses. Wallace then continued with his rebellion, which culminated in his victory at the Battle of Stirling Bridge four months later.
Previously this was an empty site, with very little indication of what once stood here. However, recently information boards were placed as well as two murals painted by Rogue One who is famous for his murals in Glasgow of Sir Billy Connolly among others.
Of course, the statue of William Wallace in a niche on the front of St Nicholas Church across the road has been there for significantly longer.
The final cache can be found by noting the following:
From "The Making of a Rebel":
King Alexander III died in ABCD
By ABEF, Wallace had become a rebel leader
From "A Life of Service":
Second paragraph, number of letters in the name of the imprisoned King = G
In February 13HG, Scots nobles made peace with Edward.
Using the information above, the cache can be found at: N 55 GH.ACE W 003 GF.AFH
Checksum: A+B+C+D+E+F+G+H = 37
The final cache can be walked to, it's downhill all the way (so uphill all the way back). Alternatively, it is possible to park closer to the final GZ, but I'll leave you to work that out, to avoid any spoilers.
Please replace the cache as found.