Do Ha-jun discovers that the blue thread leads to a closed classroom where the first missing person was found. Each time the thread is pulled, his name tag tightens.
Do Ha-jun suggests following the thread despite his name tag tightening, but leaves Serin with the right to stop.
Source stage
More discoveries
Baek I-jun fears his name might be in Bae Yu-na's final words. Still, he insists they must follow the blue thread.
Moon Ha-rin is a dawn delivery driver and the sole witness who received a delivery completion notification for a door that does not exist on the 17th floor.
Moon Ha-rin clings to the fact that the number on her non-burning visitor pass matches the order number on her thermal bag.
Seo Ji-hoo attempts to extract the cache of a sealed group chat to revive the voices of deleted residents.
