[Contains spoilers for Monday's shows]
* 24 (9 pm/ET Fox)
Talk about taking one for the team! Jack has been exposed to Starkwood's pathogen, and he's getting sicker by the hour.
This prompts the return of his daughter, Kim (Elisha Cuthbert), whose stem cells may be his only hope for a cure, but Jack is reluctant to ask for her help. Meanwhile, Tony Almeida operates in the field as Jonas Hodges and Starkwood try to blackmail President Taylor's administration.
* Heroes (9 pm/ET NBC)
The Petrellis ended last week's episode by digging up a mass grave at Angela's orders. The symbolism of that act is undeniable, then, as the Petrelli matriarch prepares to come clean about her past and many long-held secrets in tonight's installment. Mohinder, meanwhile, also spends time focusing on the past as he learns more about his dad's involvement in Project Icarus.
* Roommates (9 pm/ET ABC Family)
A mini Sister, Sister reunion occurs tonight when Tim Reid guest stars, playing the father of Tamera Mowry's character, of course. Hope's dad surprises her with a visit, and he is not happy to discover that she is now working in a coffee shop after having lost her job. He tells Hope it's time for her to move back home, leaving her so desperate to stay in the Big Apple that she'll do anything - including pretend that Mark is her boyfriend whom she's in love with and can't be apart from.
* Two and a Half Men (9 pm/ET CBS)
A man usually hopes that the woman he's in a serious relationship with will get along with his mother. Not Charlie. Tonight, Evelyn and Chelsea meet for the first time, and the last thing Charlie wants is for the woman he blames for his problems to befriend the woman he loves.
The second season closes on the crime-time character drama with the angel angle. As she continues her long-and-winding quest for divine self-actualization, girl-gone-wild Grace investigates a fatal shooting, with an elderly woman emerging as the shooter. Meanwhile, death-row inmate Leon's fall from grace culminates, as the final hours tick away to his execution. Then there's Ham, who hopes to inch closer to Grace when his divorce is finalized. Finally, it's the one named Earl: The tobacco-chomping angel may be visiting another woman, and she may hold a connection to Grace.