The visual of Misa strapped to a chair in the isolation room remains one of the series' most intense images.
That awkward yet brilliant moment when L steals Misa's phone while pretending to be a fan. Death Note Season 1 - Episode 15
Rem makes it clear that if Light does not find a way to save Misa, Rem will kill him. The visual of Misa strapped to a chair
L’s decision to go into the field and meet Misa personally was a massive risk that paid off. By "groping" Misa to swipe her phone, he effectively cut off Light’s only way to get L’s name. Death Note Season 1 - Episode 15
Explain the in more detail.