I just finished my A & P book collection, with criminal enterprise.
I'm quite disappointed by this book... if you buy a book with Aliens wrote on it, and the xenomoprh on the cover, then you find a book about drug dealers, ex cops looking for revenge and two brothers that shouldn't be where they are, with the Aliens posing just as guard dogs you can't be anything but disappointed. Especially if the author place sex any other page to get the pages required...
By the way, I think this also should be pre-invasion, since Tommy and other characters had never seen an Alien. Even if apparentrly Neo-Pharm and Grant know about those beasts.