When Mark and Hank's mother, Rhoda, shows up for an extended stay, Mark scrambles to keep her from taking over their lives by convincing Tammy she's a gifted artist, only for Tammy's "work" to become the toast of the local art scene. Meanwhile, David secretly unleashes his darkest emotions onto canvas, and Hank struggles as Rhoda completely overhauls his life.

After Mark becomes a self-proclaimed calliope prodigy and accidentally summons a troupe of clowns - including the elegant French clown Plonque Honque - he sets out to stage a prestigious clown ballet. Meanwhile, Tammy undergoes clown exposure therapy with David, unaware that Plonque has far more dangerous plans for opening night.