The episode shows three moments in the life of former Philadelphia police officer Mike Ehrmantraut (Johnathan Banks), who moved to Albuquerque to become a ticket clerk.
In a flashback, Mike Ehrmantraut leaves a train in Albuquerque and re-bandages his wounded left shoulder, then meets his daughter-in-law Stacey[a] and granddaughter Kaylee.
Matt's partner Troy Hoffman and Sergeant Jack Fensky were killed in a similar ambush six months later and the detectives suspect Mike.
Mike reveals he was feigning his drunkenness, holding the officers at gunpoint with a revolver he had hidden in the back seat when he broke into the car earlier.
Mike suggested not taking the bribes would mark him as a whistleblower, so he should accept, but Hoffman and Fensky murdered him because Matt's hesitation made them fear he would turn them in.
[4] The episode received near universal acclaim, with unanimous praise for Jonathan Banks's performance, which some critics considered award-worthy.
The site's consensus reads, "In a departure from the existing Better Call Saul narrative, 'Five-O' provides essential backstory for Mike's character, delivered in a gripping, award-worthy performance by Jonathan Banks.
She concluded, "Better Call Saul continues to deliver some of the best of what television has to offer as both those familiar with Breaking Bad and new viewers alike were given a shattering look at Mike's tragic past.