Strikers Jake Jervis and Ryan Brunt continue their good form by scoring all the Pilgrims goals in the opening 30 minutes.
New signing Jervis netted after just seven minutes when he headed home a pinpoint Gregg Wylde cross.
Brunt made it 2-0 on 23 minutes with a header from a Graham Carey corner before seven minutes later Jervis found the net again.
But in the closing stages of the half, Bath pulled a goal back through Jon Davies before having the better of the second half.
Dave Platt reduced the gap to one in the 67th minute before former Arygle player Andy Watkins levelled the match 15 minutes from time.