I Drink Your Blood

The film opens on a Satanic ritual conducted by Horace Bones, the leader of a Manson-like cult. The ritual is unknowingly witnessed by Sylvia, a young girl who has been observing them from the trees. Sylvia is eventually spotted by one of the members and is dragged in front of the group. She manages to run away but is soon caught and raped by several of the cult members. The next morning, Sylvia emerges from the woods beaten and apparently raped. She is found by Mildred, the woman who runs the local bakery, and Pete, Sylvia's younger brother. They return Sylvia home to her grandfather, Doc Banner. Mildred seeks help from her boyfriend, leader of the construction crew working on the nearby dam which has bought up most of the town leaving it deserted. The cult members' van breaks down so they elect to remain in the town. They buy pies from Mildred who explains that as most of the town is deserted and awaiting demolition they can stay in any vacant building they wish.
Learning of the assault on Sylvia, Doc confronts the cult but they assault him and force him to take LSD. Pete intervenes and Doc is released. Enraged by the incident, Pete takes a shotgun to get revenge but encounters a rabid dog which he shoots. He takes blood from the dog and the next morning injects it into meat pies at the bakery, and sells them to the cult members. Back at their house, Horace and the others eat the meat pies. The others begin to show signs of infection, and eventually they lapse into animalistic behavior. The infected members then proceed to attack and kill each other in a feral rage. One of the female members of the group, Molly becomes terrified and rushes off into the night. Construction workers sent there by Mildred's boyfriend find Molly and take her with them. Molly uses her sex appeal to insinuate herself into their group, and she spends the rest of the night having sex with all of them. Afterwards Molly begins to show signs of infection, eventually biting one of the men. Two other construction workers are killed when they venture into the house of the hippies and encounter a now-crazed Horace, who hangs one of them and guts the other. Banner discovers what is going on when Horace attacks Mildred's car and leaving bloody hand-prints behind. Andy returns to the Banner house and hides out in their barn; after making peace with Sylvia, they are discovered in the barn by Pete, who admits what he's done. Andy explains that he didn't eat the pies, therefore not infected. Banner has informed others about the potential rabies epidemic, and the next day they are joined by Dr. Oakes. Banner, Oakes, and Mildred's boyfriend all discover that the entire construction crew is now infected with rabies. Oakes and the others are nearly killed by a large group of the infected before they reach a water-filled quarry, which frightens them off.
Andy helps Sylvia and Pete escape after they discover Banner dead in the barn, impaled by a pitchfork. While running through the woods, they happen upon the pregnant hippie, who commits suicide after learning she has rabies. When they emerge from the woods, they discover Rollo and Horace lurking near the bakery; fortunately they become interested in each other, allowing the survivors to escape. Rollo and Horace clash, each of them armed, until Rollo impales Horace with a sword. Andy, Sylvia and Pete discover Mildred barricaded inside the bakery, but she is too afraid to let them inside. When she finally manages to undo the barricade, Andy is beheaded by a machete-wielding madman. Sylvia and Pete retreat with her to the basement of the bakery, but unfortunately they cannot lock the basement door. One of the infected gets inside, and Mildred shoots him in the head. They rush out of the bakery and try to drive away in Mildred's car, but crowds of the infected converge on them, overturning the car. Just then, Oakes arrives with reinforcements and they gun down the infected. Mildred, Sylvia, and Pete all emerge from the car, shaken but otherwise unharmed.[3]

Question: What does the cult force Doc to take?
Answer: LSD