Home Invasion was inspired by the TV series The Power, in which women acquired the ability to fire electric shocks from their fingertips. It removed the physical dominance men have always had. This has quite a fundamental effect on make/female relationships, so in this story the male is old, and losing strength, while the girls are super fit. And of course he can't bear to reveal the truth, that now he's weaker than girls, so he can't summon reinforcements either. Luckily everyone is good-natured in this story even though, coming from different eras, and different backgrounds, they have plenty to clash about.