When mask-wearing maniacs interrupt the reunion of a bickering family in the horror comedy You're Next, the cups of genre fans will runneth over...with blood. ''There's tons of blood,'' explains Amy Seimetz, 31, who plays a member of the cornered clan. ''Lots and lots of blood. But our family really brings out the worst in each other, so when this set of circumstances befalls them, you kind of want it to happen.'' Seimetz can also be seen this summer on AMC's The Killing and Christopher Guest's HBO comedy Family Tree. Plus, she directed the indie thriller Sun Don't Shine, now in limited release and on Amazon and iTunes. ''It's really weird that everything is out at once,'' she laughs. ''Next year, I don't know if I'll be in anything. I'll just suddenly disappear!''