The Devil transcends the details in the first one-act. The angels are vengeful caterers in the second half of "Oil & Water," this year's San Francisco Mime Troupe free show in the parks.

Paradoxes abound, and blend as uneasily as the elements in the title of the uneven show that opened Thursday before a crowd baking in the heat at Dolores Park. It looks like a traditional Mime Troupe offering, and it doesn't. It's a two-for-one deal - the price being whatever you choose to drop into the performers' hats - but the two halves add up to less than a whole.

Thematically, the one-acts tie together as a plunge into environmental issues, with an emphasis on oil politics. As co-written by the troupe's usual songwriter, Pat Moran - with Adolfo C. Mejia and the collective - and directed by company veteran Joan Mankin, both hinge on the impending Keystone Pipeline decision, though in different time periods.

"Deal With the Devil" is a futuristic semi-noir tale, a whodunit less concerned with the who than what it means. The president has been found dead in the Oval Office. The new president (Rotimi Agbabiaka) tries to take charge as D.C. insiders push him to sell America's water rights to the oil companies.

This is a post-Keystone world, so degraded that the capital sits under a climate-control dome after decades of "fracking our brains out" (the "air quality alerts," with oxygen masks popping over the wall, are a nice touch). The scenario is rich in items ripe for satire - from oil skulduggery and the president's environmentalist promises to an agency so secret that the Secret Service, FBI and Homeland Security don't know about it. But these are barely sketched in.

Only the Devil makes you sit up and take notice, because of the vitality with which Velina Brown fills the role, her bluesy ballad and Keiko Shimosato Carreiro's vibrant, mock-sexy superhero costume. Apart from her, "Devil" remains more of a skit than a full one-act.

The same is true of "Crude Intentions," minus the Devil. Set in the present, it's a San Francisco tale in which an altar-bound lesbian couple, Gracie (Brown) and Tomasa (Lisa Hori-Garcia), get enmeshed in oil skulduggery. Chevron is stalking Tomasa because of documentary footage she shot about its conviction for polluting Amazon waterways in Ecuador, a judgment it's still trying to avoid paying (look it up).

Chevron (Agbabiaka) and petro-billionaire David Koch (Hugo E Carbajal) are the supervillains, but neither is much more than a concept - except in the form of an impressive but underused giant puppet. The most effective gambit replicates the great Marx Brothers stateroom scene from "A Night at the Opera," with all four actors crammed into the women's "micro-apartment" (even more comic with no real walls).

It's a major feat for the cash-strapped Mime Troupe to have mounted a season at all. It took a last-ditch fundraising drive (a large banner details the $261,414 the season costs). The parks schedule is much shorter, the cast cut to four versatile actors and the band to only composer-lyricist-musical director Moran and Aharon Wheels Bolsta, who play like a larger ensemble.

But the show feels cut back as well. It's visually flat, in design (except the costumes) and comic stagings. Of the songs, the only standouts are the Devil's smoky blues and a catchy rap for Chevron and Koch. Despite their attractive eco-consciousness, the two thin agitprop skits don't add up to a Mime Troupe show.