In a large, dark house, someone sneaks around while a man, Robert, sleeps in a bed by himself. There is a scream and the man jumps up to find a woman at the bottom of the stairs.
At Maura's, Maura is on the phone with someone who turns out to be her bio-mom Hope. Maura explains that she is only having minor surgery and will be back home the next day. She is upset that Hope is insisting on coming. Jane tries to explain to her that mothers butt in. Angela comes in with fresh bagels and helps prove this point.
Maura cannot eat because she is having surgery. She insists on working until the surgery in the afternoon. She and Jane head off to the crime scene.
Maura obsesses over the bagels she can't eat while investigating the woman's death. Blood spatters are odd and suggest foul play. Jane wonders why Frankie showed up late rather than with Vince, especially when a uniform gives him his wallet, which he left in Nina's car. Before she can question him, the relatives are ready to be questioned.
Jane and Vince talk to Robert and his daughter Claire. Claire is heavily sedated and can't tell them much. She says she got up to go to the bathroom at 2 AM and found her mom's body. She screamed and woke her dad up.
Frankie and Nina find this doesn't quite add up as Claire was texting her boyfriend about her mom being too strict. Jane and Frankie investigate and the boyfriend admits they snuck out to a party together but Claire left before him. Claire is called in to the station and quickly lawyers up. Robert says a co-worker of his late wife suggested it.
More investigation finds that Robert lied about going to Stanford and came from a blue collar family. He had motive to kill his wife, as he would have inherited a lot of money, and his business was not doing well. Furthermore, Robert's pregnant girlfriend also died from falling down the stairs 20 years ago.
Robert takes a lie detector test and asserts his innocence. Forensic evidence suggests otherwise and Jane realizes Claire must know something. She tries to talk to her but Robert gets in the way and claims harassment.
Later, Claire calls Jane and tells her that her dad is at a storage unit. The cops catch Robert who tries to run away in his car and almost runs over a homeless man. He is caught with a bloody field hockey stick. However, the only prints on the stick are Claire's and Robert spins a story of lying to protect his daughter who is the real murderer. Frankie and Jane are forced by the DA to arrest Claire even though Jane believes she is innocent. Jane won't let Frankie cuff Claire.
Jane realizes that Robert must have dumped his bloody clothes. Trash day was yesterday so the dumpsters are empty. They track down the homeless guy who is scared of them but gives them the clothes for $30.
Robert is arrested in front of Claire, who worries she has nobody. Jane promises she has her.
Meanwhile, Maura's surgery goes well and she and her mom have a nice talk about the past and start to get closer. Maura goes with her mom to check out a volunteer opportunity at a clinic while Jane uses the lie detector to quiz Frankie about a missing hockey puck from her childhood at the Dirty Robber.