Saturday's Dusk is the secondary villain of Grim Tuesday, the second book of The Keys to the Kingdom series. As with Monday's Noon and Dusk, his appearance is very similar to Saturday's Noon, the only difference mentioned so far being their height, and that whoever fought the Lieutenant Keeper was at the time wearing a dove-grey morning coat, instead of the previously mentioned black frock coat. He was killed in Lady Friday and his brother (The youngest by a second from the same mold) took over his position. He apparently stabbed the Grim's Grotesques in Grim Tuesday.
The Dusk is briefly mentioned in Arthur's mind, and Arthur was confused why Saturday wanted the destruction of the House.
Jakem thinks that Dusk, accompanied by Internal Auditors, has flown to the Scriptorium. Friday's Dawn says that Noon has done so. For the duration of Arthur's flight to the Scriptorium, "Noon" and "Dusk" are used interchangeably.
However, in Superior Saturday it is revealed that Dusk has died. He has been replaced by his "brother", from "the same mold". It is likely that Saturday's Dusk is in charge of the Internal Auditors, the most powerful of Saturday's troops. They have quills that can shoot activated ink.
Dawn, Noon and Dusk