This study will evaluate the efficacy and safety of GSK2894512 cream for the topical treatment of plaque psoriasis (psoriasis) with its vehicle cream. This is a randomized, double-blind, vehicle-controlled, parallel-group, multicenter study in adults with psoriasis. The aim of this study is to show superiority of GSK2894512 over vehicle by comparing their response rates. The study will consist of 3 periods: up to 4 weeks screening, 12 weeks blinded treatment, and 1 week post-treatment follow-up period. Subjects will apply randomized study treatment to all psoriasis lesions once daily for 12 weeks. Subjects will be stratified by Baseline physician global assessment (PGA) category (PGA score=2, PGA score >=3) at randomization. Approximately 120 subjects will be randomized into the study of which 80 will receive GSK2894512 1% cream and 40 will receive vehicle cream. Total duration of a subject's participation in the study will be approximately for 14 to 17 weeks.