Emissary - Unseen Things, #12

How exciting would your life be if you were assigned to guard mineral deposits on an uninhabited world? Alarwyn thought that was going to be the sum total of her life, at least for the foreseeable future, but then one day, everything suddenly changed. Selected by her superiors to be their emissary to the Human dimension thanks to her friendship with Beth and Erin, she finally had a way out, but she never imagined what a life altering experience her new assignment would turn out to be.
Also, when Giles, Savaric, Billy and Sarah saved the inhabitants of dimension 3997C from an alien invasion, they had no idea of the repercussions they'd face in the aftermath. That is, until Colonel Andrew Swanson showed up at their gate one day wanting to speak to Charles and Richard. It seems that the alien invaders didn't take kindly to having their invasion fleet wiped out of existence, so they sent a ship to Earth to demand that those responsible be handed over to them within a week, or they'd launch a full-scale invasion on the planet.
The colonel was tasked with finding those responsible, but when he informs them of what's going on, the aliens very quickly discover that they should have just left well enough alone. Finally, now that Savaric has found himself someone to love, the others all take Giles out to a local club, in an attempt to find him someone as well. Fortunately, or unfortunately, as the case may be, the girl he ends up meeting turns out to be more than a handful, especially after she finds out the truth about just who and what they really are.
Emissary is book 12 of the Unseen Things series.