Despite these loose family connections, however, the three children share a bond, of mutual disappointment -- one that's kept them together throughout their lives. Renee has kids of her own with her husband, Mark (David Zayas), but she feels a responsibility for both Gary, a mild-mannered underachieving thirty-something who still lives with his mom, and especially Cassie, the youngest, who lost her mother many years ago. Cassie may be unreliable and absorbed in her own problems, but Joyce exudes a winning naivete that cuts through her character's faults.
Witty dialogue laced with strikingly truthful moments give the first act momentum that sustains through to a chilling climactic moment, but the second act gradually falls apart -- in part due to clumsy scenes such as the overlong exchange between Renee and Martin's girlfriend (Deirdre O'Connell) outside of the hospital, which threaten to bring the play to a halt. Luckily, the characters are richly drawn and equipped to fight through some of the clutter.
There is also a particularly interesting subplot involving Gary's pairing in a big brother program with a child whose mom, Angela (Megan Mostyn-Brown) is a bitch. She basically demands that Gary be the father this kid never had without ever thanking him for his volunteering. What's interesting is how he embraces this unusually harsh treatment and sees it as a way to turn his stoner life around. Indeed, no one in Thinner Than Water is faced with an easy choice as they all struggle to do what's right as their lives spiral into a messy muddle.
Mimi O' Donnell's direction is often spot-on and she elicits terrific performances from a very talented cast, especially the criminally underused Zayas, whose piercing stare can convey volumes.