Google Sheets: Reference cells and sheet determined by other cell values in the current sheet

I’ve figured out parts of how to do this, but I can’t seem to get it to work. Basically, I want to check if a range of cells in a different sheet contians only null cells. The difficult part is that I need to be able to pull both the name of the sheet that I want to check and the row of the range that I want to check from different cells in the current sheet. For example, say that I want to check the range in columns G:I, but only for a row whose value is located in cell A1 of my current sheet, in a sheet whose name is located in cell B1 of my current sheet. So, if A1 = 15 and B1 = “Sheet2” my formula in cell C1 would tell me whether the range G15:I15 in Sheet2 is null. I’ve played around a lot with the Indirect and Index functions in trying to figure this out, but I can’t seem to find a syntax that will work. I’ve managed to get it to work if I hardcode either the sheet name or the row number, but I want to avoid having to do either. Is this possible? Based on what I’ve tried so far, I feel like it has to be, I just haven’t found it yet. Any suggestions?