If it really was Si Lang who set the fire, and he had an accomplice, then it's impossible they just coincidentally met during the arson. They must have had contact beforehand.
"Stealing money, setting fires, if he really did all of this, it can't be a spontaneous act; he must have planned it in advance," Lian Manman said to Xiao Qi.
...
The carriage sped through the night, stopping only briefly in Fuyuan County before finally reaching Jinyang County as dawn approached.
Lian Manman placed many blankets in the carriage, hoping she and Xiao Qi could catch some sleep along the way. However, due to the carriage's speed and the bumpy ride, neither of them rested well.
This was their situation, not to mention Lian Shouxin who was even more anxious and worried.
The carriage entered Jinyang County Town without stopping, and upon reaching the official road leading to Thirty Mile Camp, they saw Wu Jiaxing with a few people waiting by the roadside.
