This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) the answer is unique, (iv) its answer is a continous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage 
Q: CHAPTER VIII 

A MYSTERIOUS LETTER 

In the morning mail Gus Plum received a letter postmarked London which he read with much interest. Then he called on Dave. 

"I've just received a letter I want you to read," he said. "It is from Nick Jasniff, and he mentions you." And he handed over the communication. 

It was a long rambling epistle, upbraiding Plum roundly for "having gone back on him," as Jasniff put it. The writer said he was now "doing Europe" and having a good time generally. One portion of the letter read as follows: 

"The authorities needn't look for me, for they will never find me. I struck a soft thing over here and am about seventy pounds to the good. Tell Dave Porter I could tell him something he would like to hear--about his folks--but I am not going to do it. I don't think he'll meet that father of his just yet, or that pretty sister of his either. She'd be all right if she didn't have such a lunkhead of a brother. Tell him that some day I'll square up with him and put him in a bigger hole than he got me into. If it wasn't for him I wouldn't have to stay away as I'm doing--not but what I'm having a good time--better than grinding away at Oak Hall." 

As may be imagined, Dave read this letter with even greater interest than had Gus Plum. What was said about his father and sister mystified him. 
A: 
Who sent the letter?