Late last year, the Cowsill family revisited their old New England stomping ground for an advance screening of their documentary Family Band: The Cowsills Story, which is showing through this month on Showtime.  When the movie ended that night in Gloucester MA, the siblings’ first question to the audience was, “Is everybody OK?”

It was a fair question, since the movie is more tragic then a casual fan would expect. For decades the Cowsills represented all that was sunshiney and flowery about the late ‘60s: A family so happy and wholesome that they put their mom in their band and did an ad campaign for the American Dairy Association, complete with snappy original jingle. The five brothers and kid sister Susan were well familiar to many of us ‘60s kids—They were all over 16 and the other teen magazines, and even did a prime-time special (hosted by Buddy Ebsen, of all people). Their 1968 album, the Sgt. Pepper-inspired Captain Sad & His Ship of Fools, had a story in the gatefold that rhapsodized about their family life, just the kind we all wished we had.

The truth was of course less idyllic, and Family Band spares no details.  In terms of dictatorial control, father William “Bud” Cowsill made the Beach Boys’ dad Murry Wilson look like an amateur: Adding mother Barbara to a perfectly good garage band was of course his idea, as was kicking out frontman Bill when he got rebellious. Brother Dick wasn’t allowed in the band and instead went to Vietnam, an experience that he still appears to be processing. Bud was physically violent with the brothers and worse with Susan, who describes fighting off his sexual attack one night when she just wanted to play her Cat Stevens album. Later years brought reconciliation, but also loss: The free-spirited Barry Cowsill drowned after Katrina and brother Bill succumbed to emphysema on the day Barry was buried.

The saving grace—and the reason the movie isn’t completely depressing—is that the Cowsills really believed all the groovy sentiments in the songs, and the current group can still play “The Rain, the Park & Other Things” with harmonies intact and without too much irony. Susan has lived and worked in New Orleans with husband/drummer Russ Broussard since the ‘90s (and will play French Quarter Fest next month); last year brother Bob joined their band at Carrollton Station to perform the Beatles’ White Album—all 30 songs of it, including the impossible “Revolution 9.” The movie ends with a warm-hearted latter-day song, “Some Good Years,” and by now the Cowsills’ eternal optimism looks downright heroic.