By Ken Tucker
Updated April 15, 2009 at 04:00 AM EDT
Abbot Genser/HBO

The series that makes you happy to watch other people’s heads get shrunk, In Treatment, is back for a second season of ? angry singletons, unhappy children, and miserable marrieds. And they let it all hang out ?on the sofa belonging to Gabriel Byrne’s Dr. Paul Weston. The new sessions bring us a fresh group of patients, as ? Dr. Paul speaks in soothing tones to:

Mia (indie queen Hope Davis), a successful lawyer coping badly with middle-aged loneliness; April (Milk‘s Alison Pill), a twentysomething architecture student diagnosed with cancer she’s not sure she wants to have treated; Oliver (Dirty Laundry‘s Aaron Shaw), an 11-year-old caught in the middle ?of his parents’ impending divorce; and ?Walter (Frasier‘s John Mahoney), a high-powered executive prone to panic attacks.

As it was last season, each patient gets ? his or her own episode — a half-hour HBO session — with a fifth installment given over to Dr. Paul’s own therapy visit to his mentor-shrink, Gina, played by the ever-serene ?Dianne Wiest. (Consult not your doctor ?but HBO’s schedule for its two-episodes-on-Sunday, three-episodes-on-Monday rollout of each five-episode ”week,” plus reruns.)

But if you didn’t watch In Treatment last ?season, don’t worry — they’ve made it easy ?to climb into everyone’s id. Dr. Paul has moved from Maryland to Brooklyn after divorcing his wife (Battlestar Galactica‘s mighty Michelle Forbes — we can only hope she continues to pop up for more excellent, bile-emitting ? cameos). This breakup enabled the show ?to jettison Paul’s previous, superb group of patients. But fans, do not fear: Every one of the new clients exerts a strong emotional pull.

If I had to narrow it to two standouts, I’d pick April, a sullen girl barely hiding her cancer fears behind disbelief and ? hostility. Pill’s performance captures all the shadings of a creative young woman who’s decided she’s doomed to die.

And if you know John Mahoney only as Frasier‘s lovable-grump dad, you’ll be bowled over by his transformation into a tough-as-nails executive so busy as a corporate control-freak, he can’t see the damage he’s doing to himself.

Okay, I can’t narrow it ?to just two. My heart also breaks for little Oliver as he listens to the squabbles of ?his parents (Russell Hornsby ? and Sherri Saum).

I’d be in denial, though, if ?I didn’t admit I look forward most to the sessions between Byrne and Wiest. Watching these two wily pros — both as ?actors and their characters — debate and deflect each other’s questions and answers is such a pleasure, I wish we were seeing full, real-time ?sessions. (After all, as HBO subscribers, aren’t we paying for them?)

In Treatment may be the most habit-forming TV show on the air. As I settled in for a fresh round of advice and repressed memories, ? I was reminded of the therapist’s famous last line in Philip Roth’s Portnoy’s Complaint: ”Now vee may perhaps to begin. Yes?” Yes. A