You don't know that. Same as you don't know if you could die of a pulmonary embolism sitting right there in that chair.
~ Dr. Susan Langdon to Simon.

Dr. Susan Langdon is a villainess on the ABC series, Quantico. She is a former FBI special agent who is now a forensic pathologist. She’s famous for writing a book about the “Welfare Mom Killer" she caught.

She was portrayed by Anne Heche.


Susan Langdon worked as a FBI agent and was assigned to the case of the Welfare mom serial killer who had killed up to 8 women. During the case the killer taunted her. After a ninth victim she ended up falsifying evidence to get her main suspect prosecuted. She wrote a succesfull book about how she captured him and then became a forensic pathologist.


In 2015 Dr. Langdon gave a class to FBI recruits. She tasks the NATs to look at serial killer profiles and case files and find the one murder that doesn’t fit their profile. All groups get their answers right, and Dr. Langdon tells them the real test is trying not to take home what they’ve seen. To help forget their feelings, she’s taking them out for drinks. She plays a drinking game with the students in which they challenge their knowledge on serial killers. One NAT Simon keeps pointing her at the ninth victim of the Welfare mom serial killer and points out that this victim was stabbed and not strangled like the others. Susan tries to brush it away. However he insists on wanting to talk to him. She orders a burger and takes him to a blind spot where the cameras are not filming them.

Simon tells her what he really thinks happened to victim No. 9: Dr. Langdon framed the crime scene to look like the welfare mom killer and planted evidence, so she could finally arrest him. Realizing he is on to her she threatens to kill him with a pulmonary embolism so no one will suspect it to be murder. Simon says his friends are nearby and there are cameras everywhere. Susan tells him they are in a blind spot. She uses a syringe to take him hostage and herds him out of the bar, making it look like they are going home together.

NAT Ryan sees them and follows them. He asks if everything is fine. Susan tries to keep up the charade but is forced to let go of Simon. She kisses him hard and tells him he can not prove anything.

Later her falsifying of evidence is discovered after a anonymous call and the FBI lets her killer go.


A charming teacher and famed investigator Susan Langdon has a dark side to her personality. After framing a suspect with false evidence she was willing to threaten and possibly even kill Simon to cover it up.


A cunning tactician Susan was able to isolate Simon in a crowded bar and take him hostage while pretending they were going home. Setting him up for a perfect murder as she would kill him without leaving evidence. However her scheme failed as NAT Ryan noticed the stiff manner in which Simon was herded away.