Didn't my phone have no signal?

How could I receive this call?

"Open the door, I heard your phone ringing."

I gripped my phone tightly, leaning against the door, nervously swallowing my saliva.

Just then, the phone vibrated.

It displayed a message from the delivery driver.

Trembling, I opened it.

【Hurry up, my next order is about to exceed the time limit.】

"Never mind, I'll leave it at the door."

As soon as the person outside finished speaking, the lights in my house suddenly went out.

The entire house instantly turned pitch black.

I looked outside through the peephole, and it was pitch black outside too, as if there was a power outage.

Did the circuit break?

And at that moment, I actually heard a clear knocking sound.

It wasn't the front door!

It was the bedroom door!

Someone was knocking on the door to my bedroom!

But... I thought I was the only one at home?