Lancer is about a man, Murodoch Lancer, who emigrated from Scotland in the mid-1800s, who lives on a 100,000 acre ranch where he raises cattle and horses.
When land pirates kill his foreman and seriously wound him he sends for his two sons whom he has not seen in many years.
Scott,portrayed by Wayne Maunder,is somewhere around 25, and living in Boston where he was raised by his maternal grandfather after the older man took him east when his mother died either from a fever or from childbirth. Scott served in a cavalry unit during the war and rose to the rank of Lieutenant while serving under General Phil Sheridan.
Johnny, portrayed by James Stacy, is a few years younger. Known as Johnny Madrid in certain parts of the country, Johnny's mother was Murdoch's second wife - a Mexican woman named Maria. Johnny, unlike Scott, was born at Lancer and spent approximately the first two years of his life there. For reasons known only to herself Maria deserted her husband and left Lancer with Johnny in the company of "some sort of gambler" according to Murdoch's ward, Teresa O'Brien. Johnny is saved from a firing squad by the Pinkerton agent hired to find him.
The brothers know nothing about each other's existence until they are "introduced" to each other by Teresa when they arrive on the same stage in Morro Coyo - a usually sleepy little village near the ranch.
After a rough start the boys, Murdoch and Teresa eventually become a close-knit family and share the trials and tribulations of cattle ranching and the occasional visitor from the past - be it Johnny's past as a gunfighter, Scott's past as a soldier or scion of Boston society or, occasionally, Murdoch's own past.
It is similar to, but definitely not a clone of, Bonanza. For one thing we have no idea if Murdoch is still married to Maria or if she is dead. Johnny doesn't talk about his mother much outside of the pilot episode and Cut The Wolf Loose.