One night in 1851, the fathers of young Hal Roystan (Tom Goodman-Hill, Humans) and Roddy Greenbank (Jonathan Kerrigan, Heartbeat) are killed by the same man, setting off a chain of events that brings the orphan boys together into a fateful friendship with local girl Mary Ellen (Melanie Clark Pullen, George Gently) and then drives them apart with consequences that echo on to the next generation.