糸(いと)をしっかり掴んで(つかんで)一生懸命(いっしょうけんめい)上(うえ)へ登り(のぼり)始めた

Finding the single shining spider's thread coming from above in the darkness, Kandata rejoiced greatly, thinking 'With this, I can go to Paradise!'. Grabbing the thread firmly with both hands, he began to climb up and up with all his might.