Much-loved Calleshire research chemist Derek Tridgell has been ill for some time. On his deathbed, his incessant, but unintelligible mutterings culminate in a very clear cry of foul murder. Detective Inspector Sloan and Detective Constable Crosby are brought in to investigate whether these are just the ramblings of a man at death's door, or a real confession at the final hour.

Their enquiries uncover three tragic deaths that may or may not be linked to the deceased's last words: an accidental drowning at a rival chemist manufacturer; an old friend of Derek's killed in a caving expedition whose body was never retrieved; Derek's son Paul walking away unscathed from a fatal car accident that killed one and left others irrevocably injured. With a tight-lipped Paul knowing more than he's letting on, Sloan and Crosby have their work cut out if they're going to untangle this complex case . . .