MANAMA, Bahrain— A prominent opposition figure accused by Bahrain of plotting against the state plans to return from London, an aide said Monday, in a move that could bolster protesters and force authorities into difficult choices.Hassain Meshaima, head of a group known as Haq, is scheduled to arrive late Tuesday as the embattled monarchy tries to engage demonstrators in talks aimed at easing the week-long series of clashes and marches that have deeply divided the strategic Gulf nation.A rights activist and supporter, Abbas Omran, confirmed Meshaima's plans, but gave no further details on his objections once he returns after eight months in self-exile.Meshaima is considered by Bahrain's officials as a potential enemy of the state. He and another London-based opposition leader is being tried in absentia among a total of 25 Shiite activists accused of plotting to overthrow Bahrain's Sunni rulers.