Sixth Case Achievement in The Case of the Golden Idol

You technically only need to find the clues required for the solution. Every clue in the game is marked with a ?/! and will turn into a check mark when you fully interact with them to find all the relevant details.

Solution:
Edmund Cloudsley needed a corpse. Walter Keene, along with accomplices, delivered a coffin. Upon entering, Hardy Abe suddenly clubbed David Gorran. Meanwhile, Edmund Cloudsley increased the amount of air in a sealed vase. When Hardy Abe and Jack Nails entered the room, the vase exploded and killed them both.