Didbury Toke collects and deals in antiques and works of art. Alas, he's also a fence and not always scrupulous in his dealings with non experts. It is this latter trait that leads him to rook Thomas Hobson and his wife, buying a beautiful 1692 walnut and marquetry long case clock for £2. After restoration the clock sells for about ten ten times that, but not before Toke discovers diamond jewelry hidden in its base, a treasure trove he keeps before putting the clock on the market.
Hobson's attempt to get the clock back ultimately leads to a flourishing criminal partnership between his representative, Arthur Hughes, and Toke. The former supplies stolen jewelry and other goods, the latter disposes of them. Inevitably cracks appear in the relationship, and then Toke disappears while on the continent.
The second part opens with the murder in Kent of a certain police officer known to readers of the Thorndyke stories. The deceased had gone there to dentify one Frederick Smith, and the body, robbed of official documents, is found in the Greenhithe railway tunnel. Naturally the police, Thorndyke, and Jervis are keen to catch the perpetrator.
In passing we learn Dr Jervis is married to a lady he met during one of Thorndyke's previous cases, and once this is known, the alert reader will begin to put two and two together as to how a swizz was worked, but no matter, it's still interesting to follow Thorndyke's careful investigation of a case that ultimately involves strange noises in the sealed wing of a country house and links back to the disappearance of the owner, the two-faced Toke.
My verdict: Readers who have read the previous case mentioned, particularly if they are also familiar with a certain novel by John Meade Falkner, will be a few steps ahead of Thorndyke as he unravels the inter-connected crimes, but even so it's a pretty good outing. The usual explanations of scientific doings -- and the way in which two of Thorndyke assistant Mr Polton's particularly useful inventions work -- hold interest to the end, where justice is finally done.