No shot in hell

[jouzinka]

Please, people, especially those versed in US English...

I'm translating subtitles for yesterday episode of Supernatural and this phrase jumped at me.

"Pretty much a no-shot-in-hell, hail-mary kind of thing."

We got to decode that the hail-Mary part is a reference to 1970's Dallas cowboys football, but we're still clueless about the no-shot-in-hell.

Dictionary.com and urbandictionary.com are not of much help, google sleeps.  :-(

Explanation or just pointers will be very much appreciated.

Thanks!

Here it is in context...

1767112||1769179||So, how's it going?||
1771650||1773150||Adam's gone.||
1773151||1774551||The angels have him.||
1774552||1775952||Where?||
1775953||1777287||The room where they took you.||
1777288||1778822||You sure?||
1778823||1781124||Cass did a recon.||
1781125||1782426||And?||
1782427||1784427||And the place is crawling\~with mooks...||
1784428||1787130||Pretty much a no-shot-in-hell,\~hail-mary kind of thing.||
1787131||1789966||Ah, so the usual.||
1789967||1792134||What are you gonna do?||
1792135||1793769||For starters...||
1793770||1795938||I'm bringing you with.||
1795939||1797239||Excuse me?||
1797240||1799208||There are too many of them.||
1799209||1800609||We can't do it alone,||
1800610||1804713||And, uh, you're pretty much\~the only game in town.||
1810187||1812822||Isn't that a bad idea?||
1812823||1814323||Cass and Bobby think so.||
1814324||1815959||I'm not so sure.||
1815960||1819630||Well, they're right.||
1819631||1820998||Because either it's a trap||
1820999||1822767||To get me there,\~to make me say yes,||
1822768||1825603||Or it's not a trap\~and I'm gonna say yes anyway.||
1825604||1828807||And I will.\~I'll do it... fair warning.||

[Trieste]

No shot in Hell is an emphatic "we don't have a chance". You also might see a variation of it as "He has a snowball's chance in Hell".

[jouzinka]

Oh my, that FINALLY makes sense to me, THANKIEEEEES.

[Trieste]

:)