Narniakat, you are wrong. Anita and Richard didn't get the marks until after Marcus was dead. She never feels Richard eating Marcus.
Anita and Richard recieved the marks while Gabriel was trying to rape/kill Anita.
The fact that she was pinned down while he changed on top of her is the biggest thing that freaked her out. More the being pinned under him than anything.
As for what else happenes in the book, AmethystHeart.
The big points in the book are:
1.) Richard kills Marcus and becomes Ulfric of the Pack.
2.) Gabriel & Raina capture Anita in order to use her in a snuff film.
3.) Anita and Richard take the first two marks, which help Anita save herself.
4.) Anita kills Gabriel & Raina in her escape, before going to help Richard and Jean-Claude as they were captured by a vampire.
All, in all, I would say find a way to get the book and read it, but
Anita Blake Compendium is usually a decent resource for finding out information, at least up until CS. On the homepage, they have the different covers, click on the cover of the book to get a brief summary.