hell-bent for leather

Inf. moving or behaving recklessly; riding a horse fast and recklessly. They took off after the horse thief, riding hell-bent for leather. Here comes the boss. She's not just angry; she's hell-bent for leather.

Moving recklessly fast, as in Out the door she went, hell-bent for leather. The use of hell-bent in the sense of "recklessly determined" dates from the first half of the 1800s. Leather alludes to a horse's saddle and to riding on horseback; this colloquial expression may be an American version of the earlier British army jargon hell for leather, first recorded in 1889.

Moving rapidly and with determination. “Hell” in this case strengthens the word “bent,” which means a direct route (although it sounds as though it should mean the opposite). “Leather” refers either to a saddle or to a whip used to urge a horse to move faster, or perhaps items. “Hell for leather” meaning “all deliberate haste” was a popular phrase in itself. Among a number of variants is “hell-bent for election,” said to have originated with the 1840 Maine gubernatorial race and appearing in an 1899 Stephen Crane story: “One puncher racin' his cow-pony hell-bent-for-election down Main Street.” Others are “hell-bent for breakfast,” “for Sunday,” and “for Georgia.”