Joan (Helen Twelvetrees) is a Canadian, adopted by Ma Dawson (Nellie Ferguson), a struggling horse breeder and trainer. Joan thinks "legs don't make a race horse, it's blood", and so she buys an unwanted thoroughbred colt called Stormalong. Helped by Ma's son Tommy Dawson (Frank Leighton), Joan restores the horse to health and fitness, and soon enough the horse is winning race after race, becoming a favourite for the Melbourne Cup.

Solicitor James Lord is in love with Nellie. She tells him she is going away for a week with her friend May to Portsea where there are many nice boys. Nellie gets the dates wrong and goes a day early. When James finds out he worries she is cheating on him. His client Rouse comes in and says he is convinced his wife is cheating on him a man called Dane. They hire three private eyes from Sleath's Detective Agency, Hall, Ratchet and Moon, to keep an eye on women.