At the end of 6th floor, in the elevator, Gork chat with Sara and kills her.

The issue is that i play Armory, and can not recruit new hero, so i'm unable to play further.

Also all Sara's equipment disappears.

This is no bug, you stumbled on one of the many mini story interactions. In this interaction after a six conversations, either gork kills sara or sara kills gork depending on who's stronger. If you follow closely you'll read that Gork massacred Sara's family/colony and she's the sole survivor.



Sometimes these interactions give you bonuses that can be pretty worthwhile, some trade offs, or some negative effects.



Deena and Mormish have one of my favourite interactions if you get a chance to try them out.