Bryant & May and the bleeding heart

"A teenager sees a dead man rise from his grave--and moments later is killed in a sudden hit-and-run accident. Seven ravens housed in the impenetrable fortress that is the Tower of London vanish without a trace--and legend has it that when the ravens leave, the city will fall. Bryant and May must figure out how these two inexplicable, seemingly unrelated mysteries fit together as they begin an investigation that finds them confronting a group of latter-day body snatchers and exploring the corridors of an eerie funeral parlour, all to unearth the truth behind the gruesome legend of Bleeding Heart Yard"--