Straight from James Swallow, from a Q & A on the Bolthole:
So, for my fellows Blood Angels fans...k:The title of the chapbook is Bloodline. It's a Blood Angels story that connects to the events at the end of Black Tide and events during the Horus Heresy. Rafen is one of the main characters. That's all I'm going to say for now.The games day chapbook contains a blood angels HH story : can you say anything about that ? Will sanguinius be in it ? Or Raldoron ? Who will be the main character ?
Rumour control: I'm planning that my next Horus Heresy novel (which I won't be writing for a fair while yet) will cover the battle for Signus. The working title is Fear To Tread (as in the phrase "Where angels fear to tread").It seems your new HH book is called Fear to thread and will be a blood angels novel. I assume this one is about Signus Prime ?