Darmour produced dozens of action and western features for Columbia. In 1937 he took over Columbia's popular
Jack Holt series, and signed
Ken Maynard for a series of westerns. He also produced Columbia's "Ranger" westerns with
Bob Allen and a companion series of westerns with
Bill Elliott. Darmour's name does not appear on his Columbia productions – this was company policy at Columbia, where staff producers like
Jack Fier often worked without screen credit. In 1940 Darmour was entrusted with production of Columbia's serials. Darmour, already very busy with feature films, placed serial veteran and comedy director
James W. Horne in complete charge of the serial unit. Horne freely indulged his sense of humor in such serials as
The Green Archer,
Terry and the Pirates, and
Holt of the Secret Service (Holt's last film for Darmour, and only serial). Horne's serials combine action and adventure with tongue-in-cheek comedy. Darmour was also assigned Columbia's
Ellery Queen series of detective-mystery features, which he produced through 1942. ==Illness and death==