The Shovel is the weapon used to hit Bethany Young the night she was killed. It was discovered by by The Liars in "Over My Dead Body." It was planted by "A" in a grand plan to set up the girls for Alison's murder. The shovel is currently evidence in Bethany Young's murder case.
On the night of Alison DiLaurentis' disappearence, Spencer picked up the shovel whilst fighting with Alison in the DiLaurentis backyard and attempted to attack her with it but ultimately failed. Alison and Spencer made up and Spencer went back to the barn whilst dragging the shovel behind her, which Melissa saw.
Later that night, Alison was hit in the back of the head with a rock by Charlotte DiLaurentis and buried alive underneath the gazebo construction site by Jessica DiLaurentis who was under the impression she was dead and was protecting Charlotte. Alison was pulled out of her grave by Carla Grunwald, however.
Soon after, Bethany Young wandered onto the DiLaurentis backyard, and Mona Vanderwaal hit her in the back of the head with the shovel, thinking she hit Alison. The force of the weapon was so strong it dented Bethany's skull and she was rendered unconscious. Shortly after, Melissa Hastings walked through the DiLaurentis backyard and saw Bethany's unconscious body laying on the ground with a bloody gash on the back of her head next to the empty grave. She believed it was Alison as they were wearing the same outfit and both had curled blonde hair. Melissa saw the shovel next to her and thought Spencer had attacked Alison with it and killed her. She pushed Bethany into the grave and covered her up, unaware that she was not Alison nor was she dead, unknowingly killing her by burying her alive with the shovel. Afterwards, the shovel was somehow obtained by "A."
Emily sees a rusty curved shovel perched on the barn door and affirms that the shovel must had been placed there recently. Spencer picks it up to see a note taped to the inside of the shovel, with latitude and longitude coordinates left by "A." The girls use the shovel to dig up a mannequin, which they thought had been Dr. Sullivan buried alive, before poilce helicopters begin to roar above them.
In the investigation room, Detective Wilden confronts the girls, and asserts that he has caught the girls with Alison's murder weapon, which the police have known about all along. He puts the bagged shovel from the barn on the table.
Spencer has a flashback to the night Alison disappeared using Ezra's information and recalls picking up a shovel whilst fighting with Alison. Both Jessica DiLaurentis and CeCe Drake saw this, though Jessica paid CeCe not to tell anybody.
Alison tells Spencer that she did not hit her with the shovel and instead Spencer fell and dropped the shovel. Spencer later dragged the shovel away with her. It is also revealed that Alison was not hit with the shovel as previously thought, but rather with a rock.
Melissa tells Spencer that she saw Spencer dragging the shovel away after her fight with Alison. She later found Bethany's body with a blood gash on her head and the shovel next to her and thought it was Alison's body due to the clothing and that Spencer had killed her. She buried Bethany under the impression that it was Alison and that she was protecting Spencer, who did not hit Bethany as she was asleep in the barn at the time.