这句话是定语从句么?

问题描述:

这句话是定语从句么?
The young man received a registered letter form the old gentleman in which he recalled the experience of that stormy night

in which 引导的是定语从句么?它做的是old gentleman的定语,还是letter的定语?

是letter的定语,在定语从句中做in的宾语