Daniel shouted after her.
"Marjorie!"
She stopped.
"Tell me what you put in my pool."
She looked back.
"I don't know."
Then she walked away.
Daniel lowered his phone.
His wife, Rachel, came running through the back door.
"What happened?"
Daniel pointed toward the pool.
Rachel's mouth opened.
"Oh my God."
Their seventeen-year-old daughter, Ava, appeared behind her.
"What is that?"
Daniel didn't answer.
He was looking at the bottom of the pool.
The black film was moving strangely.
Instead of spreading evenly, it was being pulled toward one specific location.
Near the main drain.
Daniel crouched beside the water.
Ava stepped closer.
"Dad."
"I see it."
Something metallic was visible beneath the dark water.
A small rectangular box.
Daniel frowned.
"That wasn't there yesterday."
Rachel looked at him.
"What is it?"
Daniel didn't know.
Ava zoomed in with her phone.
"There are letters."
"What letters?"
She enlarged the image.
Three faded characters appeared.
K-17.
Daniel's face went pale.
Rachel noticed.
"What?"
Daniel stood slowly.
"I've seen that marking before."
"Where?"
"At the construction site behind the retention basin."
Rachel stared at him.
"Why would something from that site be inside our pool?"
Daniel looked toward the fence.
Marjorie was already gone.
Then the filtration pump made a strange grinding noise.
The pool water suddenly began moving backward.
Daniel's eyes widened.
"Turn off the pump."
Rachel ran toward the control panel.
"Why?"
"Just turn it off!"
She hit the switch.
The machine died.
Silence returned.
Daniel stared at the black water.
Then he saw something floating beneath the surface.
A thin metal tag.
He reached for it with the pool net.
The tag came up dripping.
On one side was a serial number.
On the other was a warning.
BIOLOGICAL MATERIAL — DO NOT DISTURB.
Daniel looked at his family.
Nobody spoke.
Then his phone rang.
Unknown number.
He answered.
"Hello?"
A man's voice came through.
"Mr. Brooks?"
"Yes."
"You need to get everyone out of your backyard."
"Who is this?"
"My name doesn't matter."
"What is happening?"
A pause.
Then the man said something that made Daniel's blood run cold.
"That substance wasn't meant to test your pool."
Daniel gripped the phone.
"Then what was it meant to test?"
The voice answered quietly.
"Whether the contamination had reached your property yet."
The call ended.
Daniel stared at the phone.
And for the first time, he realized Marjorie Caldwell hadn't come to inspect his house.
She had come to find something.
Something that was already underneath it.
Daniel called the emergency services.
He didn't call the HOA.
He didn't call Marjorie.
And he didn't call the private security company the neighborhood used.
He called the county environmental emergency line.
The operator listened carefully while Daniel described the substance.
"Do not touch it."
"I haven't."
"Do not enter the pool area."
"Understood."
"Is anyone experiencing symptoms?"
Daniel looked at Rachel.
"No."
"Good. Leave the area until responders arrive."
"How long?"
"We're dispatching a hazardous-material assessment team."
Daniel swallowed.
"Hazmat?"
"Yes."
The word made Rachel's face change.
Ava was standing beside her, silent.
Twenty minutes later, two county vehicles entered Briarwood Estates.
Neighbors began coming outside.
People always came outside when something interesting happened.
By the time the first hazmat truck reached Daniel's house, at least fifteen residents were standing along the street.
Marjorie Caldwell appeared among them.
She was no longer wearing sunglasses.
Daniel noticed something else.
She wasn't surprised.
She looked worried.
Two hazmat technicians entered the backyard wearing protective suits.
One knelt near the pool.
The other examined the container Marjorie had left behind.
After less than a minute, he stood.
"Where did this come from?"
Daniel pointed toward the street.
"Ask her."
Marjorie stepped forward.
"I received it from a contractor."
"Which contractor?"
She hesitated.
"I don't remember."
The technician looked at her.
"You don't remember?"
"It was delivered to the association storage facility."
"By whom?"
"I don't know."
The technician opened his tablet.
"Who authorized you to handle it?"
Marjorie didn't answer.
The technician turned to Daniel.
"Sir, how much of this entered the pool?"
"Maybe three gallons."
The technician's expression changed.
"Three gallons?"
"Yes."
"Was anyone in the water?"