Leslie is upset when she learns the library department wants to take over her lot. Making matters worse, the library is run by Ron's ex-wife Tammy, who still has a powerful emotional hold on him. Meanwhile, Andy gets a job in hopes of winning Ann back.

Tom tries to get back at Ron by going out on a date with Ron's ex-wife Tammy, while Leslie tries to protect Ron from falling prey to her charms. Meanwhile, April is assigned to work with Chris.

Leslie and the parks team put together a memorial service for a dearly departed friend. Meanwhile, Tom makes a big life decision, while Chris reacts badly to a health problem.

Ron's first ex-wife, Tammy One, reenters his life and tries to control his every move. Meanwhile, Ben helps Tom balance the books at his new company, and Ann makes a PSA, with help from Chris.

Leslie has to face an ethics committee about her secret relationship with Ben after they come clean to Chris.

Ron, Diane, and Leslie attend a wood working awards dinner after one of Ron's handcrafted chairs is nominated, but the happy occasion is threatened by the arrival of Tammy II. Meanwhile, Jerry hosts a holiday party at his home with his wife, and some of his friends are shocked to find they were not invited.

Leslie, Ben, and Andy head to San Francisco for a National Parks Conference. Tom opens his restaurant, Ron has another run-in with his ex-wife Tammy 2, Andy lives a rock and roll fantasy, and Leslie makes a huge decision about her future.

Leslie and Ron briefly put aside their feud to help old foe Jeremy Jamm escape the clutches of the diabolical Tammy 2. Ben vows to help April discover her true passion in life, while Andy and Tom travel to Chicago.