It was while she was reviewing the monthly utilities bill that Irene first became aware of the ghost.
Irene considered herself a fairly organized (some would say obsessive) landlady, who carefully monitored (some would say micromanaged) the goings-on in her building. She viewed it as a preemptive defense. Certain past tenants had assumed because of her age or gender or both that they could get away with bending the rules (she would say taking advantage and costing her way too much in repairs). In response, she had evicted the worst offenders and clarified the rules to the remainder. Over time, her tenants came to respect her. As to whether this respect was begrudging or not, Irene chose not to care, so long as they behaved.
Thus, when there was a small charge in the electric bill for one of the few unoccupied apartments, Irene noticed. And, she investigated.
The number of people with access to that unit was limited, so it didn't take long. Neither the building's handyman nor the cleaning service that prepped empty units for new tenants had been in there recently. As was her policy, Irene had changed the locks after the previous resident had left, so even if a key had gone missing or been copied during that time, that would not have allowed a trespasser in now. The building was old and had no security cameras. Briefly, Irene considered installing one in the apartment in question, but as yet, the unexplained power charges added up to far less than what such a response would cost. Still, she kept an eye on it.
When a similar expense showed up on the next month's bill, Irene contacted the electric company. Once she verified her status as the building's owner, they provided her with a detailed report of the power usage in that unit. Apparently, the power flickered on and off only around 2 AM every Tuesday morning.
Irene set an alarm on her phone for the next Tuesday at 1:45 AM.
At 1:45 AM, the building felt desolate. Little creaks and rattles from the ancient heating system occasionally broke the silence, or a car passing in the street below, but other than that, quiet reigned. Irene took the back stairs with only the light of her phone screen to guide her. If there was an intruder, she didn't want the elevator or anything else to alert them. The empty unit was on the top floor, nearest the stairs. Irene had brought the spare key and at 1:57 she let herself in, locking the door behind her and settling into a corner to wait in the dark.
At exactly 2 AM, the lights flickered on. Then off. On again for a moment longer, off. Irene glanced around, keeping her face impassive but feeling her heart speed up slightly. No one was at the light switch or anywhere else in sight, nor was the switch actually flipping. The lights continued to flash, the faint buzz of the bulbs cutting in and out.
Irene wondered if there was a pattern to the flashing. Rather than waste time looking up Morse code on her phone, she opened the camera app and started a video recording. She could decipher it later; according the power company, the lights would stop flashing around 2:15 and she'd already missed the first couple rounds.
Sure enough, within fifteen minutes the lights switched off and stayed that way. Irene stopped the recording, got to her feet, and took one last look around. Her eyes were still adjusting to the dark, but nothing seemed out of place. To the empty room she said, “You know, there's more energy efficient ways of communicating.” As she expected, there was no response.