Complex sentence: When Purdy doesn't hear from either officer, he shows up in person and surprises Fisby in a bathrobe used as an improvised kimono, and McLean in a yukata, leading a rowdy song at a party in full swing in the teahouse.
Split into simpler sentences: When Purdy doesn't hear from either officer, he shows up in person and surprises Fisby and McLean, the latter wearing a yukata. Both are leading a rowdy song at a party in full swing in the teahouse.