Warwickshire agonisingly fell 10 runs short as Northants took the spoils at Moseley Cricket Club.
Batting first, the visitors reached 263 for 9 from their 50 overs with opener Charlie Thurston top scoring with 50.
George Panayi was the pick of the bowlers with figures of 10-0-37-2, whilst George Garrett (9-0-46-2), Dan Mousley (8-0-45-2), Tom Milnes (10-1-42-1) and James Cox (8-1-47-1) all chipped in.
The Bears response started slowly as they reached 45 for three, but Matt Lamb (54 from 83) and Alex Mellor (91 from 84, six fours, three sixes) steered Warwickshire to 154-5, just 109 runs short.
But when Lamb departed, the tail were unable to form a partnership with Mellor.
Stone, who is slowly returning and didn’t bowl, made three batting at seven whilst Panayi gave the Bears hope with 18 from 24.
Mellor continued to anchor an end and push Warwickshire victory in the final stages, but he was caught by Thurston with the hosts needing 11 from nine to win.