You, your wife, and your pre-teen daughter live in a two-story home on a five-acre lot in a rural subdivision eight miles outside of town, accessed by a frontage road that parallels the interstate highway. Other than highway noise and occasional singing coyotes, it had always been a quiet neighborhood. But conditions in town have been worsening over the last couple of months since an influx of illegal migrants relocated there into temporary housing by the federal government. Many of them are good people who mean no harm, but among them are some hardened gang members who quickly forged connections with local criminals, or moved on their operations and territory, especially on the drug traffickers using the interstate. 

There's been a significant uptick in violence and property crime in town, and last week two homes in your area were targeted – one vacant when it was burglarized, and one subjected to a home invasion by armed, masked intruders while the family was asleep in their beds. The homeowner was shot and is still under critical care at the hospital, his family has taken refuge with relatives across town, and the Sheriff's office says at least one intruder was wounded, as evidenced by the blood trail left behind. The Sheriff has been candid: you are going to be responsible for your own safety. The uptick in most categories of crime, and his ongoing recruiting and retention problems, translate into an estimated response time for his deputies of 15-30 minutes at best to all unincorporated areas in the county. The police in town face similar problems, but worse. 

Your house has front and rear entries, a sliding glass door to an outside deck in back, an attached garage, and an alarm system that, in overnight mode, delivers a visual and audible alert to your mobile phone when any ground floor door or window is opened or broken. The child's bedroom is at the opposite end of the second floor hallway from the parents' room. The ground floor living room has a vaulted ceiling and is overlooked by the second floor open hallway. The open stairs climb from the ground floor to the second floor at the end of the hallway nearest the parents' room.

At 2:00 in the morning, you are awakened from a sound sleep by a loud crash downstairs, and a simultaneous light and tone alert from your phone. Grabbing the phone, you see that the back door has been opened.

You and your wife each keep a loaded Glock 19 9mm handgun, with a weapon-mounted light and an extra magazine, in your nightstand. You both took a 24-hour handgun course last summer, and have conducted varying amounts of dry- and live-fire practice at the range once or twice a month since.

Your wife wakes up as you are looking at your phone; you both hear multiple footsteps on the wooden downstairs flooring, and muted voices. Your daughter cries out from her bedroom, "Daddy?!?" Your wife grabs you by the arm and asks:

​ "What do we do now?"​