《猜火車》主角是愛丁堡的五個年輕朋友，以及他們的毒癮生活。本片最神奇的一點，是它內容雖醜惡絕望，卻又極為生氣蓬勃。它的敘事角度、對話風格、音樂選擇等等皆獨樹一格，將想像與現實融合的手法充滿炫麗，加上幾位新銳演員的亮眼表現，使《猜火車》成為90年代經典電影之一。
五位主要角色以伊旺麥奎格飾演的Renton戲份最重要，但另外四位也各有鮮明特色，包括腦袋總在雲端的Spud、超迷007的Sick Boy、原本不吸毒但被女友甩掉後忍不住加入的Tommy、以及不吸毒但對人很殘暴的Begbie。
這群人好端端的為何要吸毒？很簡單，因為爽。Renton還特別強調，不理解他們的人老以為吸毒者是因為太蠢了才碰毒，但卻忽略了真正的吸引力是什麼──吸毒實在爽歪歪。不都說減法人生才能輕鬆嗎？那麼吸毒就是減到極致了。清醒的話，要擔心工作、家庭、房貸、未來……但如果吸海洛因，就只需擔心一件事：海洛因。如何拿到更多海洛因。簡單過生活。
但如果說，《猜火車》是在崇尚、鼓勵吸毒文化，那就把它看小了。
在展示完吸毒有多令人自在後，《猜火車》也將可怕的後果呈現出來。例如Renton後來在戒斷時，腦中浮現的死嬰畫面，令人明白他永遠會被這件事附身著。生活原本就不該簡單，不能簡單。「簡單」是會有後果的，它只是延後問題，並未解決問題。唯一能夠永不面對問題的方法，只有早死。這群人為了規避社會的枷鎖，找來另一種同樣很難逃出去的枷鎖。
在這些個案的背後，有令人無力的大環境──未來充滿不確定感與無望感帶來的虛無主義。如果正常世界只不過是個悲劇的殭屍世界，機械性、無意義、窮忙半天也不會有大好人生，那麼如何勸人不吸毒？旁觀者又幫他解決了什麼現實問題？或許海洛因是這群蘇格蘭年輕人在殘酷經濟環境下，唯一可觸及的快樂。就連不吸毒的主要角色，都有自己的癮頭：Begbie喝酒、傷人不眨眼，Tommy抽煙，Renton的媽媽靠煩寧(Valium)度日。
Renton是幾個主角之中，最努力也最有機會解救自己的人，但是過去一直找上他，而他清醒生活中的「無聊」，也讓觀眾很難不去注意。即使到了電影尾聲，似乎靠著背叛獲得某種解脫，他的未來依舊是個大問號，因為有太多得逃避一輩子的東西。青春的魯莽能量，他已經用盡，過了某個人生階段後，很難再回頭過那種充滿活力但毫無方向的日子，必須開始償還年輕時欠下的人生債。或許也因如此，二十年後的續集《猜火車2》讓許多《猜火車》的影迷引頸企盼，實在太好奇Renton會遭遇什麼事情、用什麼樣的態度來待人處世。
二十年前電影裡的Renton，在Iggy Pop的"Lust for Life"歌曲中極速奔跑躲警察，他是青春的、快樂的、自由的，他周圍奉公守法的人們是無趣的、壓抑的、無奈的；當他在「全蘇格蘭最髒的廁所」裡的噁心馬桶內尋找丟失的毒品，大腦感受到的情境是在清澈神秘的水域悠遊，現實的齷齪一點也傷害不到他，簡單的希望（毒品）就在前方，伸手就可拿到，努力就有報償，這是多麼美的烏托邦。當然大家都明白，這不可能持續下去，只是當我再度溫習《猜火車》，想起自己曾有過的魯莽青春與自由心境，終究有著遺憾。如何找回"Lust for life"？還是它永遠不會再回來了？聽著《猜火車》結尾Renton的獨白，我知道他跟我都接受了人生的無奈。
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經典對白：
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Mark "Rent-boy" Renton: [narrating] Choose Life. Choose a job. Choose a career. Choose a family. Choose a fucking big television, choose washing machines, cars, compact disc players and electrical tin openers. Choose good health, low cholesterol, and dental insurance. Choose fixed interest mortgage repayments. Choose a starter home. Choose your friends. Choose leisurewear and matching luggage. Choose a three-piece suit on hire purchase in a range of fucking fabrics. Choose DIY and wondering who the fuck you are on Sunday morning. Choose sitting on that couch watching mind-numbing, spirit-crushing game shows, stuffing fucking junk food into your mouth. Choose rotting away at the end of it all, pissing your last in a miserable home, nothing more than an embarrassment to the selfish, fucked up brats you spawned to replace yourselves. Choose your future. Choose life... But why would I want to do a thing like that? I chose not to choose life. I chose somethin' else. And the reasons? There are no reasons. Who needs reasons when you've got heroin?
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Mark "Rent-boy" Renton: Now I've justified this to myself in all sorts of ways. It wasn't a big deal, just a minor betrayal. Or we'd outgrown each other, you know, that sort of thing. But let's face it, I ripped them off - my so called mates. But Begbie, I couldn't give a shit about him. And Sick Boy, well he'd done the same to me, if he'd only thought of it first. And Spud, well okay, I felt sorry for Spud - he never hurt anybody. So why did I do it? I could offer a million answers - all false. The truth is that I'm a bad person. But, that's gonna change - I'm going to change. This is the last of that sort of thing. Now I'm cleaning up and I'm moving on, going straight and choosing life. I'm looking forward to it already. I'm gonna be just like you. The job, the family, the fucking big television. The washing machine, the car, the compact disc and electric tin opener, good health, low cholesterol, dental insurance, mortgage, starter home, leisure wear, luggage, three piece suite, DIY, game shows, junk food, children, walks in the park, nine to five, good at golf, washing the car, choice of sweaters, family Christmas, indexed pension, tax exemption, clearing gutters, getting by, looking ahead, the day you die.
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Tommy: Doesn't it make you proud to be Scottish?
Mark "Rent-boy" Renton: It's SHITE being Scottish! We're the lowest of the low. The scum of the fucking Earth! The most wretched, miserable, servile, pathetic trash that was ever shat into civilization. Some hate the English. I don't. They're just wankers. We, on the other hand, are COLONIZED by wankers. Can't even find a decent culture to be colonized BY. We're ruled by effete arseholes. It's a SHITE state of affairs to be in, Tommy, and ALL the fresh air in the world won't make any fucking difference!
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Mark "Rent-boy" Renton: We took morphine, diamorphine, cyclizine, codeine, temazepam, nitrazepam, phenobarbitone, sodium amytal, dextropropoxyphene, methadone, nalbuphine, pethidine, pentazocine, buprenorphine, dextromoramide, chlormethiazole. The streets are awash with drugs you can have for unhappiness and pain, and we took them all. Fuck it, we would have injected vitamin C if only they'd made it illegal.
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Mark "Rent-boy" Renton: [on a high] Take the best orgasm you've ever had... multiply it by a thousand, and you're still nowhere near it.
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《猜火車》主角是愛丁堡的五個年輕朋友，以及他們的毒癮生活。本片最神奇的一點，是它內容雖醜惡絕望，卻又極為生氣蓬勃。它的敘事角度、對話風格、音樂選擇等等皆獨樹一格，將想像與現實融合的手法充滿炫麗，加上幾位新銳演員的亮眼表現，使《猜火車》成為90年代經典電影之一。