Yes, it's the show that your grandmother watches. No, it's not a just a serious version of Psych.
Now that we've gotten that out of the way...
"How am I supposed to know who you are? You're banging on my door: 'CBI! CBI!' Like that's supposed to mean something?"
"Yeah, we do need better brand awareness."
-- 1x21 "Blood Brothers"
The Mentalist is a CBS show about the Serious Crimes Unit of the California Bureau of Investigation and the titular mentalist who works as their consultant. They are "like the FBI, only more conveniently located" and offer their assistance in murder cases that are difficult, or just high-profile, when they're not tracking down the serial killer Red John.
The show is on the smarter and more liberal end of the procedural spectrum, and though on the surface it's more cute and whimsical than realistic and gritty, it has a dark and disturbing underbelly like some unholy union between Castle and Dexter.
Also, it has one of the most messed up main characters on primetime TV.
( The characters )( Why should you watch this thing? )( Where can you watch this thing? )