Margin Call (Lionsgate, Blu-ray or standard DVD, R, 107 min.). This film looks at the onset of the mortgage meltdown that triggered the financial crisis of 2008 by focusing on about 27 hours at one firm. It does so in a way that is both understandable and intense, as the knowledge of impending doom is passed up the ladder of the company and decisions are made on how to react.

It is about closing time the day the film opens and there is a major purge of the staff at the New York City investment firm. One of those let go is senior risk analyst Eric Dale (Stanley Tucci) who is informed, with no notice, that he is gone after 19 years and will be given six months at half-pay. His cell phone is shut off and he is escorted to his office to pack his things and then escorted out of the building. On his way out, he hands a subordinate (Zachary Quinto of TV’s “Heroes” and “American Horror Story” as Peter Sullivan) a flash drive with the program he has been working on and tells Peter to be careful. While those left celebrate at a local bar, an intrigued Peter stays behind and works on what Eric gave him, coming up with the missing data. What the program shows is the company’s risk model for the mortgages they have been packaging as investments has already gone past acceptable limits. When Peter realizes the projected losses would be greater than the value of the company, he calls co-worker Seth Bregman (Penn Badgley, whose character is obsessed with making money) at the bar and tells him to bring back Eric’s boss (Paul Bethany as Will Emerson). Will then calls his boss (Kevin Spacey as Sam Rogers), who is having a tough day anyway as his dog has to be put down.

Sam becomes the voice of conscience in the piece when the top dogs — Simon Baker as Jared Cohen and Jeremy Irons as CEO John Tuld, who helicopters in around 3 a.m. — decide to sell as much of the worthless holdings as fast as they can the next morning, fully realizing they are burning bridges with the buyers. In effect, the remaining workers will be selling themselves out of a job. While the firm is not named, Tuld’s name is close to that of Richard Fuld, CEO of Lehman Brothers.

The acting is excellent throughout. Also in the cast are Demi Moore as the head of the risk management division and Mary McDonnell as Sam’s divorced wife. Extras include two deleted scenes (one with Tuld giving the workers a pep talk), a 6-minute making of look, moments with the cast and crew, a photo gallery and commentary by writer/director J.C. Chandor and the producer Neal Dodson.

Rating guide: 5 stars = classic; 4 stars = excellent; 3 stars = good; 2 stars = fair; dog = skip it

Additional reviews are available online at villagesoup.com and include “Dolphin Tale” and “Futurama Vol. 6.”