When the pair got in, came up the stairs, walked over to the safe, the infra-red beam would break, tripping relays that set off small water-streams that would go all ways around the safe, charged with a current that could chain a marauder in his tracks. Doctor Ryder, knowing about it, would stay out of range, sending his captor, the miscreant they wanted, to his defeat.
They crouched, Roger behind the recording device, Grover in the office, Tip near the stairs to the upper floor, the Falcon guards at three strategic points near ground-floor windows.
There was the silence of a deserted building as they waited.
Minutes passed. The intruding thief was careful, Roger decided.
Still more time passed draggily.
Roger began to grow cramped, and also very uneasy in his mind.
What was going on? Was it so wise to wait? Why not throw on some light. Better sidle over and ask Grover? No. Better wait.
He strained his ears.
He heard only what seemed to be the drip of a faucet in the chemical washing-sinks. Tick! Tick-et-y—tick. Silence. Tick! Tic-tic—tick-y. A wait. Tick-tick.
He tried to focus his hearing on any other possible sound. The drip-drip effect seemed to cease. He wondered about it, but decided that it had not been a faucet but had been a few drops of collected water running down the drain and striking in the trap.