Complex sentence: With his memories regained, Shu rescues Inori from Shuichiro's clutches in his plans to transplant Mana's soul into her body so he and Mana will spread the outbreak worldwide and start a new race.
Split into simpler sentences: With his memories regained, Shu rescues Inori from Shuichiro's clutches. Shuichiro had plan to transplant Mana's soul into Inori's body, so Shuichiro and Mana (in Inori's body) would spread the outbreak worldwide and start a new race.