Murder Mystery House

The logbook contains entries only through June 2016. Since all of those entries are present in the display cabinet, none of those can be the missing item.

The gold mask illlustrated in the sketchbook is not in the cabinet, but there is a receipt showing that it is currently on loan to the prestigious Mercury Gulch Historical Society.

The description from Barkers Auction House of the Keru cup suggests that they were always used in pairs. You should look at the sketchbook to see if that is the same or a different cup from the one purchased from Barkers.

You know the log numbers for only the 6 items in the logbook. However, there was a formula used to generate those log numbers. Each entry is a combination of different pieces of information about each item.

The missing Keru cup's country of origin would be the same as that of the other Keru cup - Peru. So the log number for the missing item starts with the letter P.

The acquistion note from Robert Black mentions the lot number for the missing Keru cup as 1447, so the first part of the log number is P1447.

The number after the dash in each log number is the year it was acquired. The note from Robert Black says that the Keru cup was acquired "last December". Given that the note is dated February, 2021, the previous December would be 2020.

The log number for the Keru cup is P1447-20.