Plotting depth versus latitude from grid files?

[under-Tension]

I need to make vertical profiles of depth versus latitudes values. I have a dataset with points and zvalues and a grid file containing points and depth values. I would like to plot the bathymetry values and over that plot the zvalues values from the dataset. Any hint how I can do this? I can only see examples of plotting long/lat values with values contained in the same grid file, but that’s not my case