Flanked by winged cherubs and bearing a family coat of arms, it is a monument that erected itself, in a sense: the Latin inscription records that Sir Henry Piers built the tomb on his own initiative, a point the text takes care to emphasise.

The plaque is dated 1620, though Sir Henry Piers did not die until 1623, which means he commissioned and installed his own memorial while still living. The inscription, translated in the Annals of Westmeath in 1907, describes him as a man of renowned piety and illustrious stock who repaired the house of Tristernagh, constructed an adjoining road, and renovated the church itself before placing the monument within it. It closes with a direct address to whoever might be reading: his soul, the text says, thou reader, assist by your prayers. Beneath the plaque are the remains of a seventeenth-century chest tomb, a long rectangular stone box of the kind common in Hiberno-English memorial tradition. A quotation from Psalm 87 runs across the top: Misericordias Domini in Aeternum Cantabo, meaning I will sing of the mercies of the Lord for ever. By 1826, a visitor recorded that the chapel served as the sepulchral vault of the Piers family. The lower panel extends the memorial to Henry's father, William Piers, described as a very brave and liberal Chief; his mother was Anne Holt, his wife Jane, daughter of Thomas Jones, Chancellor of the kingdom, and of Margaret Purdon. The Piers family seat, Tristernagh House, stood nearby, and the ruins of Tristernagh Abbey lie some 570 metres to the north-east, placing this small graveyard within what was clearly a landscape of some significance to the family across several generations.