The saddest thing about Lioness: Hidden Treasures, the first posthumous release from Amy Winehouse, is that it's merely a perfectly enjoyable collection of odds and ends that intermittently hints at the tortured-soul complexity that made the doomed British singer such a compelling - and sometimes great - artist.

That's because Winehouse, whose alcohol-poisoning death in July was tragically unsurprising, never conceived Lioness (Universal Republic ***) to be the follow-up to Back To Black, her 2006 five-time Grammy winning second album.

According to producer Salaam Remi, who worked on Hidden Treasures along with fellow knob twiddler Mark Ronson, Winehouse did finish writing a sequel to Back to Black, the album which spawned both her defiantly destructive signature song, "Rehab" and the excellently existential hit "You Know I'm No Good."

She never got around to recording it, however. There are rumors that Winehouse cut a reggae album in 2009 that was rejected by her record label, who saw it as a dangerously non-commercial change of direction. And last month, Remi told reporters that at the time of her death Winehouse was planning on forming a supergroup of sorts with British saxophonist-and-rapper Soweto Kinch and ubiquitous Roots drummer Ahmir "?uestlove" Thompson.

But all signs indicate that when Winehouse died she did not leave an enormous trove of unreleased recordings behind, a la Tupac Shakur. Instead, as with Kurt Cobain, there appear to be a smattering of songs, some dating from an earlier innocent and not yet artistically mature period in her career, along with a precious few others that tantalizingly hint at what might have been.

In the former category are a handful of covers, such as the reggae-flavored take on Ruby & the Romantics' "Our Day Will Come" and a Wall of Sound build-up of Gerry Goffin and Carole King's "Will You Still Love Me Tomorrow?" There's an undeniable sweetness to those songs - and a scat-singing cover "The Girl From Ipanema" - date as far back as 2002, preceding the Winehouse's debut album, Frank, which came out the next year.

Those covers don't plumb the depths nearly so thoroughly as the modernized and melancholic updated girl-group musings made Back To Black so powerful, there're still delivered with a creeping sense of dread that came naturally to the Billie Holiday-influenced singer.

That sense of looming darkness is more pronounced on Hidden cuts like the moody-blue "Half Time," a woozy jazz ballad, that features ?uestlove on drums. It also hovers over "Like Smoke," a haunting Winehouse chorus that was completed posthumously with a pair of somewhat jarring verses, complete with Occupy Wall Street references, from Nas, Winehouse friend and maybe boyfriend who's said to be the subject of Back to Black's "Me and Mr. Jones."

And it's also there on Lioness' two Back to Black alternative versions, a slowed down string decorated "Tears Dry" and a stripped down demo of  "Wake Up Alone." The latter, in particular, serves as a reminder that along with being a coolly confident, warmly emotive singer, skilled at slurring syllables to maximize a lyric's mystery, Winehouse was a sharp, self-analytic writer.

That may have been lost on anyone who knew Winehouse through tabloid coverage of her often-sordid public and private life, rather than her music.  But it can be heard anew Lioness' stunning, depressive and more heartbreaking than ever "Wake Up Alone": "I stay up, clean the house, at least I'm not drinking / run around, just so I don't have to think about thinking / That silent sense of content that everyone gets, just disappears as soon as the sun sets."

"Half Time" is below.

Previously: RIP, Hubert Sumlin Follow in The Mix on Twitter here