What plan did Horace Danby make to rob the house at Shotover Grange? (A Question of Trust)

Horace planned the robbery in all details. A magazine article had described the house with all the rooms and mentioned the safe behind the painting. For $\displaystyle 2$ weeks, he studied the house, its rooms, electric wiring, path and its garden / knew the dog by name He had definite information that the two servants had gone to the movies. He came out from behind the garden wall. Packed his tools carefully on his back. Put on gloves, knew the hosuekeeper hung the key to the kitchen door on a hook inside. He took the key and opened the house.