The story begins with a small-time Con Man named John (David White) being released from prison, whereupon his mentor, Rome (Eric Roberts), tries to talk him into doing One Last Job. Instead, John rips off the seed money, hoping to invest it in a legitimate real-estate deal. When Rome discovers the deception, John flees, accidentally loses the money, and desperately seeks out his estranged twin brother, Jeremiah (also played by White).
Before the brothers can meet, Rome abducts Jeremiah, believing him to be John — and John decides to pose as Jeremiah. A few things complicate this: Jeremiah is a preacher, his housemate is a policeman, and his girlfriend, Sam (Cynthia Watros), just rejected his marriage proposal.
As John improvises his way through this unfamiliar milieu, his priorities gradually change: first he's focused on raising money to go through with the land deal; then he's taken with Sam and patches things up with her on Jeremiah's behalf; then his anger at Jeremiah for abandoning him to apparent death when they were teenagers resurfaces, and he seeks revenge by verbally abusing Sam to alienate her and "confessing" to his own murder in an attempt to sabotage Jeremiah's career.
In the mean time, Rome, unwilling to lose his million-dollar scam, presses Jeremiah into service as John's replacement. John will be framed for a murder otherwise, and Jeremiah, racked with guilt, is unwilling to abandon his brother again.
Mercy Streets teeters on the edge between Troperiffic and Cliché Storm, particularly in its unironic use of Twin Tropes.
This film provides examples of:
- Angsty Surviving Twin: A slight variant in the backstory; Jeremiah felt guilty because he believed John to be dead, leading to much emotional confusion when he learns the truth.
- Bald of Authority: Jeremiah's religious superior, Father Dan.
- Bad Habits: John wears clericals to impersonate his brother, an Episcopalian deacon.
- Bookends: The film begins and ends with a character getting out of prison.
- Christian Rock: Features prominently in the soundtrack.
- Christianity is Catholic: Averted; Jeremiah dresses in clericals, but he's an Episcopalian clergyman.
- Contrived Coincidence: Near the end, John and Jeremiah run into each other completely by chance — and they are wearing identical shirts, with predictable results.
- Covers Always Lie: The VHS box blurb, as well as at least one version of the tagline, refers to Jeremiah as a priest. Actually, he hasn't been ordained a priest yet. He's a deacon.
- Dartboard of Hate: Downplayed: In John's Stalker Shrine, one picture of Jeremiah is affixed to the bulletin board with a single dart to the forehead.
- Fish out of Water: After they switch places, John and Jeremiah have a fair amount of trouble adapting to one another's lifestyles. John has a somewhat easier time of it: he is able to fake righteousness, but Jeremiah is deeply unwilling to participate in a crime.
- Funny Answering Machine: Sam's. "Leave me a message... or else."
- Gender-Blender Name: Sam, who is Jeremiah's girlfriend.
- Good Smoking, Evil Smoking: The criminals smoke (John cigarettes, Rome cigars); the good guys don't. And in the last scene the reformed John chews on a toothpick, implying that he's quit.
- Just Got Out of Jail: The film opens with John being released from prison. Later in the story, Jeremiah takes a fall for him so he won't be a two-time loser.
- The Mafiya: Used as an off-screen menace.
- The Moral Substitute: It's a pastiche of neo-noir gangster films — but with toned-down violence, no sex or swearing, and an overt religious message.
- The Precious, Precious Car: TJ's beloved El Camino. John mars it to needle TJ, and later Rome secures his compliance by seizing it.
- Plethora of Mistakes: Interesting in that even inconsequential details seen onscreen during the Mission Briefing, but never mentioned in the voiceover, go wrong in reality — the edges of the blank paper turn out to be a slightly different color than those of the bills, and TJ's tattoos are not completely hidden.
- Polar Opposite Twins: John and Jeremiah. John is an embittered, streetwise petty criminal; Jeremiah is a straitlaced minister.
- Stalker Shrine: A mild case; John keeps several newspaper clippings about Jeremiah, including a very old one, on his bulletin board.
- Tattooed Crook: Rome's associate TJ is played by the heavily tattooed character actor Robert LaSardo.
- Wicked Cultured: Rome seems to be trying for this, particularly in his fondness for gourmet cooking.
