The story follows their plan to use Ìyábọ́'s frequency detector to locate the exact source of the 99.9 signal where Táíwò and other missing people are being held. While Káyòdé creates a distraction with false signals, Rírì hides inside a blue rain barrel to get close enough to the tower for accurate readings.

As specified in your prompt, the rain drums "bùm-bùm-bùm" on the barrel surface, creating both cover and tension. Aṣàkẹ́ whispers updates through her radio while her teeth chatter from fear and cold as she watches for security.

The suspense peaks when a security guard's boot steps stop right beside Rírì's barrel. The guard stands there for what feels like eternity, his flashlight beam dancing around the barrel opening while rain continues drumming on the plastic surface. Only increased distraction from Káyòdé's false signals draws the guard away at the crucial moment.

The chapter ends with the revelation that the frequency detector picked up signals from 20-30 people in the basement, not just Táíwò. This escalates their mission from a single rescue to a mass liberation operation, raising the stakes significantly.

The rain barrel becomes both literal hiding place and metaphor for the precarious position of their resistance - protected by thin walls while surrounded by overwhelming force.