If it's a British crime drama, I'm in. Broadchurch. Happy Valley. Line of Duty. Sure, there's some terrible ones too (I haven't been enjoying Ragdoll, and gave it up after one episode) but as a general rule of thumb, they're good at it. However, I shied away from The Beast Must Die after I read 'after the death of her six year old son'. That seemed so terrible and tragic I didn't think I could face watching it. Howe…