The series opens with Mary and Des administering assisted suicide drugs (sodium pentobarbital in a glass of champagne) to Troy Dixon who has a moment of indecision and Mary takes the time to talk to him about whether it’s what he wants to do. Troy drinks the champagne and seems to drift off but as Mary and Des are preparing to leave, Troy’s wife returns home unexpectedly. They rush to get away but then Troy revives in medical distress and he asks Mary to smother him with a pillow. Mary and Des jump off the balcony to get away and hit a drive-thru to pick up dinners for Mary and her daughters. While waiting for their food, they discuss why Troy revived and Des insists that the drug should be injected instead of administered in a drink and offers to give the shot in future cases if Mary won’t.

Mary gets home to find her daughters, Jess and Cambie, in the bathroom trying to summon up Bloody Mary’s ghost with candles and chanting in the dark. While eating dinner, they discuss whether ghosts exist and Mary tells her younger daughter that they don’t but the dead stay in the hearts of the living. Mary’s ex-husband, Kevin, comes by to pick up the girls so that Mary can work a night shift at the hospital. They argue about how busy she’s been lately with Kevin accusing her of being the second absentee parent.

Alone, she heads down to the shed where she’s hidden her stash of pentobarbital and notices that all the seals on the bottles have been tampered with. She calls Des to let him know because he’s in charge of getting the drugs.

At the hospital, Mary insists of fighting to save the life of a young knife wound victim despite his flatlining and her fellow doctor declaring him “gone”. They are able to bring him back and stabilize him which the other doctor takes credit for although Mary cautions him that it’s early days yet. Later, she meets with Annie, a nurse, who passes on two files of people looking for assisted suicide options.

One of the files Annie passes on is Joel’s and he phones and leaves a message for Mary and Des, asking for help to die and then hits a strip club with a friend where they discuss what death is like.

Des goes to his dealer’s home to get a fresh supply of pentobarbital and Grady questions whether all the supply is for Des’ use. Grady’s concerned that Des is using his product to deal to other people himself. When Des calls him on watering down the pento, he admits that he did to see if Des was really using it. He provides Des with a fresh supply, guaranteed to be pure, but doesn’t think Des is telling the truth.

Mary’s older daughter Jess takes her friend, Naomi, to the shed after their dance practice to smoke a joint and make out. Mary’s burner cellular phone starts buzzing while they’re there and the girls find the stash of diluted pento.

Mary and Des visit Joel and have a consultation meeting and Joel insists that he wants to die. As the drive away, Des encourages Mary to go out and have a fling, picking up on some of the attraction that sparked between Joel and Mary during their meeting. Mary is resistant as Joel’s a patient.

Mary arrives at Jess’ dance recital and sits down next to Kevin and Cambie and is introduced to Naomi’s mother, Louise, who is apparently dating Kevin now. Once the lights go down for the show, Mary passes Kevin an envelope of cash for her alimony payment. Naomi collapses on stage and Jess calls for her mother to help. They get her to the hospital where she revives and tells Mary that she took some of the pento before the show, thinking it was alcohol, to help her with her stage fright. She insists that Mary not tell her Louise because she’s a lawyer.

Once Naomi’s taken home, with her mother clueless as to the true cause of her collapse, Mary’s colleague from the surgery earlier in the day approaches her to ask her to tell the stab victim’s wife that he’ll need another surgery. The other doctor doesn’t want to deliver the bad news, insisting that Mary’s just better at it.

Leaving the hospital, she gets a voicemail from Joel, saying that he’s thought things over and he’s ready to take the next step. She heads straight over and they discuss why she does what she does for people. When the conversation gets more intense, she tries to kiss him and he pushes her away hard enough for her to fall and hit her head. When he helps her up, he gives in and they start to have sex but when she makes the whispered observation that he doesn’t seem sick, he comes to his senses and pushes away again. Getting his pants zipped up, he wants her to give him the death drink right there and then and she has to explain that she doesn’t have it with her and that there’s protocol to follow. He asks, angrily, if the sex was part of the protocol and she runs out the door. He follows her out and apologizes and tries to get her to come back into his apartment. She drives away.

Once she’s gone, a van across the street flashes its lights and Joel crosses the street. His buddy from the strip club, Frank, is inside and the two of them are part of a sting trying to get evidence on Mary. Frank was supposed to leave earlier but passes Mary when she was entering the building so he stayed and turned on the recording devices in Joel’s apartment, catching everything that was said as well as Joel having sex with the target. Joel convinces Frank to get rid of the tape of the sex by bringing up perjury that he committed for Frank’s sake the previous year. They’ll get Mary and Des recorded bringing in the drugs for the euthanasia the next day as planned and arrest them then.

When Mary gets home, Jess is in the shed looking at the hiding spot where she and Naomi had found the pento. She tells Mary that she thinks Naomi might’ve taken some of the pento and asks her mother why she’s keeping drugs in the shed. Mary covers by saying that their cat, Casper, has cancer and she wanted to put him down at home where he would be more comfortable. Naomi asks why everything – her parents, Naomi, and the car – is messed up and Mary counsels her to hold on.

Mary takes Casper to Des’ place, interrupting some quality time with a pothead girlfriend, and confessing that she’d had sex with Joel which Des thinks is great. Confused by Joel’s reaction after their sex, she asserts that they need to end his suffering tomorrow. In a final scene, Troy Dixon’s widow is having a cry in their bed, hugging one of Troy’s jackets and finds the pamphlet that Mary and Des circulate to potential clients.